Infusion Pump Assembly

ABSTRACT

An infusion pump assembly is disclosed. The infusion pump assembly includes a locking tab and a pump barrel inside a pump barrel housing, where the pump barrel accommodates a reservoir assembly. The reservoir assembly includes a reservoir and a plunger rod. The infusion pump assembly also includes a locking disc at a terminus of the pump barrel. The locking disc includes a clearance hole for the plunger rod. The locking disc also includes at least one locking tab notch in close proximity with the locking tab. The locking tab is in moveable engagement with the locking tab notch, and the reservoir moves the locking tab from a locked position to an unlocked position when the plunger rod is inserted through clearance hole. The locking disc rotates upon torque being applied to the reservoir assembly, the locking disc rotating from a non-loaded position to a loaded position with respect to the plunger rod and a drive screw.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.14/500,082, filed Sep. 29, 2014 and entitled Infusion Pump Assembly, nowU.S. Pat. No. 9,308,318, issued Apr. 12, 2016 (Attorney Docket No. P01),which is a Continuation of U.S. patent application Ser. No. 12/413,234,filed Mar. 27, 2009 and entitled Infusion Pump Assembly, now U.S. Pat.No. 8,845,587, issued Sep. 30, 2014 (Attorney Docket No. H23), which isa Continuation of U.S. patent application Ser. No. 12/249,891, filedOct. 10, 2008 and entitled Infusion Pump Assembly, now U.S. Pat. No.8,034,026, issued Oct. 11, 2011 (Attorney Docket No. G46), which is aContinuation-In-Part of U.S. patent application Ser. No. 11/533,882,filed Sep. 21, 2006 and entitled Infusion Set for a Fluid Pump, now U.S.Pat. No. 9,173,996, issued Nov. 3, 2015 (Attorney Docket No. E62), whichis a Continuation application of U.S. patent application Ser. No.10/151,733, filed May 20, 2002 and entitled Infusion Set for a FluidPump, which is now U.S. Publication No. US/2002-0173769 published Nov.21, 2002, which is now abandoned (Attorney Docket No. D13). U.S. patentapplication Ser. No. 11/533,882 also claims priority from U.S.Provisional Patent Application No. 60/291,881, filed May 18, 2001 andentitled Cannula Designs for Insulin Pump Systems (Attorney Docket No.C63), each of which are hereby incorporated herein by reference in theirentireties.

U.S. patent application Ser. No. 10/151,733 is a Continuation-In-Partapplication of U.S. patent application Ser. No. 10/037,614, filed Jan.4, 2002 and entitled Loading Mechanism for Infusion Pump, now U.S. Pat.No. 7,306,578, issued Dec. 11, 2007 (C54). U.S. patent application Ser.No. 10/151,733 also claims priority from U.S. Provisional PatentApplication No. 60/291,881, filed May 18, 2001 and entitled CannulaDesigns for Insulin Pump Systems (C63), both of which are herebyincorporated herein by reference in their entireties.

TECHNICAL FIELD

This disclosure relates to pump assemblies and, more particularly, toinfusion pump assemblies.

BACKGROUND

An infusion pump assembly may be used to infuse a fluid (e.g., amedication or nutrient) into a user. The fluid may be infusedintravenously (i.e., into a vein), subcutaneously (i.e., into the skin),arterially (i.e., into an artery), and epidurally (i.e., into theepidural space).

Infusion pump assemblies may administer fluids in ways that would beimpractically expensive/unreliable if performed manually by nursingstaff. For example, an infusion pump assembly may repeatedly administersmall quantities of an infusible fluid (e.g., 0.1 mL per hour), whileallowing the user to request one-time larger “bolus” doses.

SUMMARY OF DISCLOSURE

In accordance with one aspect of the present invention, an infusion pumpassembly is disclosed. The infusion pump assembly includes a lockingtab, and a pump barrel inside a pump barrel housing, where the pumpbarrel accommodates a reservoir assembly. The reservoir assemblyincludes a reservoir and a plunger rod. The infusion

pump assembly also includes a locking disc at a terminus of the pumpbarrel. The locking disc includes a clearance hole for the plunger rod.The locking disc also includes at least one locking tab notch in closeproximity with the locking tab. The locking tab is in moveableengagement with the locking tab notch, and the reservoir moves thelocking tab from a locked position to an unlocked position when theplunger rod is inserted through clearance hole. The locking disc rotatesupon torque being applied to the reservoir assembly, the locking discrotating from a non-loaded position to a loaded position with respect tothe plunger rod and a drive screw.

Some embodiments of this aspect of the present invention may include oneor more of the following features. The locking disc may further includea second locking tab notch, wherein the second locking tab notch isengaged with the locking tab when the locking disc is in the loadedposition. The locking disc may further include a plunger rod support.The plunger rod support may be in close relation with the plunger rodwhen the plunger rod is inserted through the clearance hole. The lockingdisc may further include at least two reservoir tab openings for matingwith at least two reservoir alignment tabs on the reservoir. Thereservoir assembly may further include a locking hub. The locking hubmay fluidly connected to the reservoir. The locking hub may furtherinclude at least two locking hub alignment tabs, the locking hubalignment tabs aligning with the reservoir alignment tabs when thelocking hub is fluidly connected to the reservoir. The infusion pumpassembly may further include a hub and battery end cap. The end cap mayhave an opening to the pump barrel. The pump barrel opening may becomplementary to the locking hub alignment tabs wherein the loading ofthe reservoir assembly may provide alignment of the reservoir alignmenttabs with the reservoir tab openings and the plunger rod with theclearance hole. The hub and battery end cap may further include a firstalignment feature. The first alignment feature may be complementary to asecond alignment feature on the reservoir. When the first and secondalignment features are aligned, the locking hub alignment tabs may alsobe aligned with the hub and battery cap opening.

In accordance with one aspect of the present invention, a reservoirassembly is disclosed. The reservoir assembly includes a reservoir, thereservoir having an interior volume and terminating with a male featureon a first end. Also, the reservoir assembly includes a plunger rod, theplunger rod including a threaded portion and a notched portion. Theassembly further includes a reservoir bottom, the reservoir bottomhaving a plunger rod opening, and at least two reservoir alignment tabs,wherein the plunger rod extends through the plunger rod opening.

Some embodiments of this aspect of the present invention may include oneor more of the following features. The reservoir assembly may furtherinclude an alignment feature on the reservoir. The alignment feature mayallow aligning the reservoir assembly with an infusion pump assembly forloading the reservoir assembly into the infusion pump assembly. Aremovable filling aid may be included having a threaded portion and ahandle portion. The threaded portion may thread to the threaded portionof the plunger rod.

In accordance with one aspect of the present invention, a method ofloading a reservoir assembly to a drive mechanism of an infusion pumpassembly is disclosed. The method includes aligning locking tabalignment features of a reservoir and locking tab assembly with analignment feature on a hub and battery end cap of the infusion pumpassembly, applying pressure to the locking tab of the reservoir andlocking tab assembly, and rotating the locking tab until the locking tabis flush with the infusion pump assembly. Rotating the locking tab loadsthe reservoir and locking hub assembly onto the drive mechanism of theinfusion pump assembly.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features andadvantages will become apparent from the description, the drawings, andthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B are front and back isometric views of an infusion pumpassembly;

FIGS. 1C-1E are side and front views of the infusion pump assembly ofFIG. 1;

FIG. 1F is a front isometric view of the infusion pump assembly of FIG.1;

FIG. 2 is a diagrammatic view of the infusion pump assembly of FIG. 1;

FIG. 3A is a top-level view of an infusion pump according to oneembodiment;

FIG. 3B is an exploded view of a drive mechanism for the infusion pumpof FIG. 3A;

FIG. 3C is an isometric views of one embodiment of a reservoir andlocking hub assembly according to one embodiment;

FIG. 3D is an exploded isometric view of a locking hub and a reservoiraccording to one embodiment;

FIG. 3E is an isometric view of one embodiment of the reservoirassembly;

FIG. 3F shows an embodiment of a pump barrel locking mechanism;

FIG. 3G shows a magnified view according to FIG. 3F;

FIGS. 3H-3I shows the relation of the drive screw to the plunger rod forthe infusion pump of FIG. 3A;

FIG. 3J shows a connection from one embodiment of a reservoir to atubing set;

FIG. 3K illustrates another method of connecting one embodiment of areservoir to a tubing set;

FIG. 3L shows an adapter for using a small diameter reservoir with thepump assembly according to one embodiment;

FIGS. 3M-N are on-axis views of the adapter of FIG. 3L;

FIG. 4A is an exploded view of one embodiment of the reservoir andlocking hub assembly with portions of the loading and drive assembly ofone embodiment of the infusion pump assembly;

FIGS. 4B-4D are partial views of the loading of the reservoir assemblyonto the drive assembly;

FIGS. 4E-4F are top and bottom views of the hub and battery end capaccording to one embodiment of the infusion pump apparatus;

FIG. 4G-4I are bottom, side and top views, respectively, of oneembodiment of the locking disc;

FIGS. 4J-4L are isometric views of one embodiment of the locking disc;

FIGS. 4M-4N are partial illustrative views of the loading of thereservoir assembly onto the drive assembly of one embodiment of theinfusion pump apparatus;

FIG. 5 A is an isometric view of one embodiment of the plunger andplunger rod apparatus;

FIG. 5B is an isometric view of one embodiments of the reservoir andlocking hub assembly;

FIG. 5C is an isometric view of the plunger and plunger rod apparatusaccording to the reservoir and locking hub assembly shown in FIG. 5B;

FIGS. 5D-5E are isometric and cross sectional views, respectively, ofthe plunger seal apparatus according to one embodiment;

FIG. 5F is a cross sectional cut-off view of the assembled plungerapparatus of FIG. 5C;

FIG. 5G-5P are various embodiments of the plunger seal apparatus;

FIGS. 6A-6B are views of one embodiment of the filling aid apparatus;

FIGS. 6C-6D are isometric views of the filling aid apparatus of FIGS.6A-6B together with a plunger rod, both attached to the plunger rod anddetached from the plunger rod, respectively;

FIGS. 6E-6F are isometric views of one embodiment of the filling aidapparatus together with a plunger rod, both attached to the plunger rodand detached from the plunger rod, respectively;

FIGS. 6G-6I are isometric views of alternate embodiments of the fillingaid together with a plunger rod;

FIGS. 7A-7B are isometric views of various portions of one embodiment ofthe infusion pump assembly;

FIGS. 7C-7D are isometric views of the reservoir assembly together withthe drive screw and the strain gauge according to one embodiment of theinfusion pump apparatus;

FIG. 7E is an magnified isometric view of a plunger rod together with anoptical displacement sensor according to one embodiment of the infusionpump apparatus;

FIGS. 8A-8D are various alternate embodiments of the reservoir assembly;

FIGS. 9A-9B are cross-sectional views of a medium connector assemblyincluded within the infusion pump assembly of FIG. 1;

FIGS. 9C-9D are cross-sectional views of a medium connector assemblyincluded within the infusion pump assembly of FIG. 1;

FIGS. 9E-9F are cross-sectional views of a medium connector assemblyincluded within the infusion pump assembly of FIG. 1;

FIGS. 9G-H are cross-sectional views of a medium connector assemblyincluded within the infusion pump assembly of FIG. 1;

FIGS. 9I-J are cross-sectional views of a medium connector assemblyincluded within the infusion pump assembly of FIG. 1;

FIG. 10A is an isometric view of a removable cover assembly for use withthe infusion pump assembly of FIG. 1;

FIG. 10B is an alternative isometric view of the removable coverassembly of FIG. 10A;

FIG. 10C is a cross-sectional view of the removable cover assembly ofFIG. 10A;

FIG. 11 is an alternative isometric view of the removable cover assemblyof FIG. 10A;

FIG. 12A-12D are isometric views of an alternative embodiment of theremovable cover assembly of FIG. 4;

FIG. 13 is a diagrammatic view of the infusion pump assembly of FIG. 1;

FIG. 14 is a flowchart of a process executed by the infusion pumpassembly of FIG. 1;

FIG. 15 is a flowchart of a process executed by the infusion pumpassembly of FIG. 1;

FIG. 16 is a timeline illustrative of a plurality of discrete infusionevents;

FIG. 17 is a more detailed view of two discrete infusion events includedwithin FIG. 16.

FIG. 18 is a diagrammatic view of a storage array included within theinfusion pump assembly of FIG. 1;

FIG. 19 is a flowchart of a process executed by the infusion pumpassembly of FIG. 1; and

FIG. 20 is an illustrative view of one embodiment of a remote controlassembly.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1A-1F, there is shown an infusion pump assembly 100that may be housed within enclosure assembly 102. Infusion pump assembly100 may include display system 104 that may be visible through enclosureassembly 102. One or more switch assemblies/input devices 106, 108, 110may be positioned about various portions of enclosure assembly 102.Enclosure assembly 102 may include infusion port assembly 112 to whichcannula assembly 114 may be releasably coupled. Removable cover assembly116 may allow access to power supply cavity 118 (shown in phantom onFIG. 2).

Referring to FIG. 2, there is shown a diagrammatic view of infusion pumpassembly 100. Infusion pump assembly 100 may be configured to deliverinfusible fluid 200 to user 202. Infusible fluid 200 may be deliveredintravenously (i.e., into a vein), subcutaneously (i.e., into the skin),arterially (i.e., into an artery), and epidurally (i.e., into theepidural space). Examples of infusible fluid 200 may include but are notlimited to insulin, nutrients, saline solution, antibiotics, analgesics,anesthetics, hormones, vasoactive drugs, and chelation drugs, and anyother therapeutic fluids

Infusion pump assembly 100 may include processing logic 204 thatexecutes one or more processes that may be required for infusion pumpassembly 100 to operate properly. Processing logic 204 may include oneor more microprocessors (not shown), one or more input/outputcontrollers (not shown), and cache memory devices (not shown). One ormore data buses and/or memory buses may be used to interconnectprocessing logic 204 with one or more subsystems.

Examples of the subsystems interconnected with processing logic 204 mayinclude but are not limited to memory system 206, input system 208,display system 104, vibration system 210, audio system 212, motorassembly 214, force sensor 216, and displacement detection device 218.Infusion pump assembly 100 may include primary power supply 220 (e.g. abattery) configured to be removable installable within power supplycavity 118 and to provide electrical power to at least a portion ofprocessing logic 204 and one or more of the subsystems (e.g., memorysystem 206, input system 208, display system 104, vibration system 210,audio system 212, motor assembly 214, force sensor 216, and displacementdetection device 218).

Infusion pump assembly 100 may include reservoir assembly 222 configuredto contain infusible fluid 200. In some embodiments, reservoir assembly222 may be a reservoir assembly similar to that described in U.S. PatentApplication Publication No. US 2004-0135078-A1, published Jul. 15, 2004,which is herein incorporated by reference in its entirety. In otherembodiments, the reservoir assembly may be any assembly in which fluidmay be acted upon such that at least a portion of the fluid may flow outof the reservoir assembly, for example, the reservoir assembly, invarious embodiments, may include but is not limited to: a barrel with aplunger, a cassette or a container at least partially constructed of aflexible membrane.

Plunger assembly 224 may be configured to displace infusible fluid 200from reservoir assembly 222 through cannula assembly 114 (which may becoupled to infusion pump assembly 100 via infusion port assembly 112) sothat infusible fluid 200 may be delivered to user 202. In thisparticular embodiment, plunger assembly 224 is shown to be displaceableby partial nut assembly 226, which may engage lead screw assembly 228that may be rotatable by motor assembly 214 in response to signalsreceived from processing logic 204. In this particular embodiment, thecombination of motor assembly 214, plunger assembly 224, partial nutassembly 226, and lead screw assembly 228 may form a pump assembly thateffectuates the dispensing of infusible fluid 200 contained withinreservoir assembly 222. An example of partial nut assembly 226 mayinclude but is not limited to a nut assembly that is configured to wraparound lead screw assembly 228 by e.g., 30 degrees. In some embodiments,the pump assembly may be similar to one described in U.S. Pat. No.7,306,578, issued Dec. 11, 2007, which is herein incorporated byreference in its entirety.

During operation of infusion pump assembly 100, infusible fluid 200 maybe delivered to user 202 in accordance with e.g. a defined deliveryschedule. For illustrative purposes only, assume that infusion pumpassembly 100 is configured to provide 0.00025 mL of infusible fluid 200to user 202 every three minutes. Accordingly, every three minutes,processing logic 204 may provide the appropriate drive signals to motorassembly 214 to allow motor assembly 30 to rotate lead screw assembly228 the appropriate amount so that partial nut assembly 226 (andtherefore plunger assembly 224) may be displaced the appropriate amountin the direction of arrow 230 so that 0.00025 mL of infusible fluid 200are provided to user 202 (via cannula 114). It should be understood thatthe volume of infusible fluid 200 that may be provided to user 202 mayvary based upon, at least in part, the nature of the infusible fluid(e.g., the type of fluid, concentration, etc.), use parameters (e.g.,treatment type, dosage, etc.). As such the foregoing illustrativeexample should not be construed as a limitation of the presentdisclosure.

Force sensor 216 may be configured to provide processing logic 204 withdata concerning the force required to drive plunger assembly 224 intoreservoir assembly 222. Force sensor 216 may include one or more straingauges and/or pressure sensing gauges and may be positioned betweenmotor assembly 214 and an immovable object (e.g. bracket assembly 232)included within infusion pump assembly 100.

In one embodiment, force sensor 216 includes four strain gauges (notshown), such that: two of the four strain gauges are configured to becompressed when driving plunger 222 into reservoir assembly 222; and twoof the four strain gauges are configured to be stretched when drivingplunger 222 into reservoir assembly 222. The four strain gauges (notshown) may be connected to a Wheatstone Bridge (not shown) that producesan analog force signal (not shown) that is a function of the pressuresensed by force sensor 216. The analog force signal (not shown) producedby force sensor 216 may be provided to an analog-to-digital converter(not shown) that may convert the analog force signal (not shown) into adigital force signal (not shown) that may be provided to processinglogic 204. An amplifier assembly (not shown) may be positioned prior tothe above-described analog-to-digital converter and may be configured toamplify the output of e.g., force sensor 216 to a level sufficient to beprocessed by the above-described analog-to-digital converter.

Motor assembly 214 may be configured as e.g., a brush-type DC electricmotor. Further, motor assembly 214 may include a reduction gear assembly(not shown) that e.g. requires motor assembly 214 to rotatethree-thousand revolutions for each revolution of lead screw assembly228, thus increasing the torque and resolution of motor assembly 214 bya factor of three-thousand.

FIG. 3 A is an overall view of an infusion pump according to oneembodiment. A pump assembly 300 contains the components needed to causea reservoir assembly 302 to deliver medication or any liquid to a user.The reservoir assembly 302 may contain enough liquid, e.g., medication,such as, but not limited to, insulin, for several days for a typicaluser. A tubing set 304, connected to the reservoir assembly 302,includes a cannula (not shown) through which the medication is deliveredto the user.

Referring also to FIG. 3B, an exploded view of one embodiment of thedrive mechanism of the infusion pump is shown. Reservoir assembly 302may include reservoir 306, plunger 308 and plunger rod 310. Reservoir306 may contain the medication for delivery to the user and is ofvariable interior volume. The interior volume may be the liquid capacityof reservoir 306. Plunger 308, may be inserted into the bottom of thereservoir 306, and may cause the volume of reservoir 306 to change asplunger 308 is displaced along the longitudinal axis of reservoir 306.Plunger rod 310 may be connected to plunger 308 with the plunger rod'slongitudinal axis displaced from and parallel to the longitudinal axisof reservoir 306. Plunger rod 310 may be threaded for at least a portionof plunger rod's 310 length. As shown in this embodiment, cylindricalpump barrel 312 receives reservoir assembly 302. Pump barrel 312 mayconstrain plunger rod 310, orienting plunger rod 310 along thelongitudinal axis of pump barrel 312. Pump barrel 312 may be containedin pump assembly 300 and, in some embodiments, may contain locking tab317, which may prevent rotation of pump barrel 312 with respect to pumpassembly 300. Gear box 316 in pump assembly 300 may include drive screw314 along with motor and gears to turn drive screw 314. Drive screw 314may be threaded and the screw's longitudinal axis may be alignedparallel to and may be displaced from the longitudinal axis of pumpbarrel 312. Locking hub 318 may be attached to the top of reservoir 306.

Referring now to FIGS. 3C-3D, one embodiment of reservoir assembly 302together with locking hub 318 is shown. Reservoir 306 may be sized toaccommodate any volume desired. In the exemplary embodiment, reservoir306 may accommodate a volume of 2.5 ml, however, in various otherembodiments, reservoir 306 may be sized to accommodate a smaller orlarger volume. As discussed above, reservoir 306 volume may change asthe plunger is displaced along the longitudinal axis of reservoir 306.In the exemplary embodiments, locking hub 318 may be connected to tubingset (not shown, an embodiment of the tubing set is shown in FIG. 3A as304) such that the liquid in the reservoir may flow through the lockinghub to the tubing. In some embodiments, such as the exemplary embodimentshown, reservoir 306 may also include reservoir alignment tabs 307 andreservoir bottom 305.

Still referring to FIGS. 3C-3D, plunger rod 310, in the exemplaryembodiment, may include a threaded portion 320 and a notched portion322. The threaded portion may thread to drive screw 314. Notched portion322 may be used, in the exemplary embodiment, to encode informationrelating to reservoir assembly 302, including but not limited to theinformation, the methods and devices described in U.S. PatentApplication Publication US 2004/0135078 A1, published on Jul. 15, 2004and entitled Optical Displacement Sensor for Infusion Devices, which isherein incorporated by reference in its entirety.

Referring also to FIG. 3D, the exemplary embodiment of locking hub 310and mating male portion 324 of reservoir 306 are shown. Reservoir 306 isshown without reservoir bottom 305, which is shown in FIG. 3C. Thetapered luer connection is described in more detail below. As shown inFIG. 3D, locking hub 310 may include a

female part 329 as well as tab 326, while reservoir 306 may include amale part 324 as well as slot 328. Male part 324 and female part 329 maymate to form a luer connection. Tab 326 and slot 328 may lock togetherwhen mated and turned, one part relative to its mating part, such thattab 326 may slide into the slot 328.

Referring now to FIGS. 3E, another embodiment of reservoir assembly 330is shown. In this embodiment, hub portion 332 and reservoir portion 334are connected, and in one embodiment, are molded as a single part.

Referring also to FIG. 3F, a pump barrel locking mechanism for anembodiment of the device is shown. The pump barrel 312 includes aclearance hole (not shown, shown in FIG. 3H as 340) that guides theplunger rod 310 during insertion of the reservoir assembly 302 into thepump barrel 312. To ensure that the drive screw 314 does not interferewith the plunger rod 310 during insertion of the reservoir assembly 302,the pump barrel 312 maintains a fixed position relative to the pumpassembly 300. The position of the pump barrel 312 relative to the pumpassembly 300 may be maintained, for example, by a locking tab 317included in the pump barrel 312 that engages a pump barrel stop 342 inthe pump assembly 300. The locking hub 318 may include a flange 338which dislodges the locking tab 340 from the pump barrel stop 342 whenthe locking hub 318 turns, allowing the locking hub 318 to rotate thepump barrel 312.

Referring also to FIGS. 3G-3H, these FIGS show views along thelongitudinal axis of the pump barrel 312 showing the relation of thedrive screw 314 to the plunger rod in a loading position and in anengaged position, respectively. The reservoir assembly 302 is positionedfor loading so that the plunger rod 310 does not contact the drive screw314, as shown in FIG. 3G. With the pump barrel 312 positionedappropriately with respect to the pump assembly 300, the plunger rod 310clearance from the drive screw 314 is determined by the placement of theclearance hole 340 in the pump barrel 312 base, which hole 340 receivesand guides the plunger rod 310. The clearance hole 340 may be tapered toease insertion of the plunger rod 310. The drive screw 314 fits in a

clearance hole 340 in the pump barrel 312. Once the reservoir assembly302 is inserted into the pump assembly 300, the pump barrel 312 isrotated by the locking hub 318, causing the plunger rod 310 to turn andto engage the drive screw 314, as shown in FIG. 3H. This embodimentadvantageously simplifies reservoir loading.

In some embodiments, the plunger rod threads and the drive screw threadsare buttress threads. These embodiments may be advantageous in that theyeliminate reaction forces on the plunger rod normal to the direction ofthe rod's longitudinal axis. Such reaction forces may cause the rod todeflect and skip a thread on the drive screw, resulting in underdelivery of medication to the user. Buttress threads eliminate thenormal component of the reaction force.

Referring also to FIG. 31, in some embodiments, the locking hub 318 maybe connected to the reservoir 306 by a tapered luer connection. Thereservoir 306 has a male luer taper integrally molded into thereservoir's top 344. Surrounding the male luer is an annulus with aninternal female thread. Similarly, the locking hub 318 contains themating female luer and threaded male connection.

In another embodiment, a needle connection is provided between reservoir306 and locking hub 318. As shown in FIG. 3J, the reservoir includes arubber septum 346 that is attached to the reservoir with a crimped metalcollar. A needle 348, integral to the hub, pierces the septum and fluidcan then flow from the reservoir to the tubing set.

In other embodiments, as shown in FIG. 3K, an adapter 350 is provided topermit a reservoir 352 whose diameter is substantially smaller than thediameter of a pump barrel to be used with the pump assembly 300. Theadapter 350 may be a separate component or may be integrated into thelocking hub 354. The locking hub 354, in some embodiments, may be one ofthe embodiments described herein, and sized accordingly. The adapter 350aligns and offsets the reservoir's 352 axis parallel to the longitudinalaxis of the pump barrel so that the plunger rod 356, when rotated, mateswith the drive screw (not shown). FIGS. 3L-3M show an on-axis view ofthe small diameter reservoir 352

when placed in the adapter 350. As will be apparent, the offset providedby the adapter allows the plunger rod 356, when mated with the plunger308 and reservoir 352, to engage the drive screw 314 in a similarfashion as for the first embodiment, described above.

Referring now to FIG. 4A, another embodiment of the drive mechanism foran infusion pump is shown. As shown in this embodiment, a cylindricalpump barrel 312, shown here inside a pump barrel housing 360, receivesthe reservoir assembly 302. The pump barrel 312 terminates with alocking disc 400. The pump barrel 312 constrains the plunger rod 310,orienting the plunger rod 310 along the longitudinal axis of the pumpbarrel 312. The pump barrel 312 is contained in the pump barrel housing360, which is contained in the pump assembly 300. The locking disc 400,in the exemplary embodiment, contacts a locking tab (shown in FIG. 4B as402), which is in the pump gear box 364. The locking tab 402 preventsrotation of the locking disc 400 with respect to the pump assembly 300.However, in some embodiments, the locking disc 400 may not include alocking tab 402. A gear box 364 in the pump assembly 300 includes adrive screw 314 along with motor and gears to turn the drive screw 314,and, as discussed above, in some embodiments, a locking tab 402 forlocking the locking disc 400. The drive screw 314 is threaded and thescrew's longitudinal axis is aligned parallel to and displaced from thelongitudinal axis of the pump barrel 312. A locking hub 318 is attachedto the top of the reservoir 306.

Still referring to FIG. 4A, in the embodiment shown, the plunger rod 310is connected to the plunger 308. In the exemplary embodiment, theplunger rod 310 and plunger 308 are a single molded part. O-rings 366fit over the plunger 308. However, in some embodiments, the O-rings maybe molded into the plunger 308.

Referring back to FIGS. 3C-3D, the locking hub 318 additionally includeslocking hub alignment tabs 325. As shown in FIG. 3C, once the lockinghub 318 and reservoir 306 are mated, the locking hub alignment tabs 325and the reservoir alignment

tabs 307 are aligned with one another. Referring also to FIGS. 4E-4F,the pump assembly 300 includes a hub and battery end cap 404. The hubsection of the hub and battery end cap 404 includes complementaryopening for the locking hub 318, including the locking hub alignmenttabs 325.

Thus, once the reservoir assembly 302 is mated with the locking hub 318,to load the reservoir into the pump barrel 312, the reservoir must beoriented correctly with respect to the locking hub alignment tabs 325and the complementary opening in the hub and battery end cap 404. Thereservoir alignment tabs 307 will thus also be aligned with the lockinghub alignment tabs 325.

Referring now also to FIGS. 4G-4L the locking disc 400 is shown. Thelocking disc 400 includes a clearance hole 340, which, in the exemplaryembodiment is tapered for easy insertion, but in some embodiments, isnot tapered. Additionally, the reservoir tab openings 406, plunger rodsupport 412 and first and second locking tab notches 408, 410 are shown.As discussed above, the reservoir alignment tabs 307 are aligned withthe locking hub alignment tabs 325. The orientation assured by the huband battery end cap 404 assures that the plunger rod 310 will be in thecorrect orientation to fit through the clearance hole 340, the reservoiralignment tabs 307 will mate with the reservoir tab opening 406, and thereservoir bottom 305 displaces the locking tab 402.

In some embodiments, the locking disc 400 may include only a firstlocking tab notch 408, or, in some embodiments, may not include anylocking tab notches. The locking tab notches 408, 410 maintain theorientation of the locking disc 400 for ease of loading the reservoirand locking hub assembly. Also, the second locking tab notch 408contributes to maintaining the plunger rod 310 and drive screw 314relationship. Additionally, although the reservoir tab openings 406 areincluded in the exemplary embodiment of the locking disc 400, someembodiments of the locking disc 400 do not include reservoir tabopenings 406. In these embodiments, the reservoir does not includereservoir alignment tabs 307 (shown in FIGS. 3C-3D).

In the exemplary embodiment, the reservoir tab openings 406, togetherwith the reservoir alignment tabs 307, aid in the rotation of thelocking disc 400. When loading the reservoir and locking hub assemblyinto the pump assembly 300, the user, having aligned the reservoir andlocking hub assembly with the hub and battery cap 404, drops thereservoir and locking hub assembly into the pump barrel 312 and appliesa slight pressure to the locking hub 318. The user then applies torqueto the locking hub 318 to complete the loading process. Where thelocking disc 400 includes the reservoir tab openings 406 and thereservoir includes the reservoir alignment tabs 307, as in the exemplaryembodiment, the torque applied to the locking hub is transmitted fromthe reservoir alignment tabs 307 to the locking disc 400 rather thanfrom the locking hub 318 to the plunger rod 310. Thus, in the exemplaryembodiment, the reservoir alignment tabs 307 together with the reservoirtab openings 406 work together to take up the torque applied to thereservoir and locking hub assembly which contributes to maintaining theintegrity of the plunger rod 310 while also ensuring proper engagementof the plunger rod 310 onto the drive screw 314.

Referring also to FIG. 4B, bottom view of the locking disc 400 is shownwith the locking tab 402 engaged with one of the locking tab notches408. The clearance hole 340 is shown empty of the plunger rod. Thus, thelocking disc 400 is shown in the locked, non-loaded position. The drivescrew 314 is shown and the plunger rod support 412 is also shown.Referring now also to FIG. 4C, the plunger rod 310 is shown having fitthrough the clearance hole 340. The reservoir alignment tabs 307 areshown having mated with the reservoir tab openings 406, and the lockingtab 402 is deflected from the locking tab notch 408.

The plunger rod support 412 is shown along part of the plunger rod 310.The plunger rod support 412 contributes to maintaining the integrity ofthe relationship of the plunger rod 310 and the drive screw 314 suchthat the drive screw 314 of the plunger rod 310 maintain connection andthe plunger rod 310 is not deflected.

Referring now also to FIG. 4D, the locking disc 400 is shown afterrotation and reservoir loading is complete, i.e., in the loadedposition. The plunger rod 310 is engaged to the drive screw 314. Thesecond locking tab notch 410 is now engaged with the locking tab 402.Thus, the locking disc 400 is locked from continuing further rotation.

Referring also to FIGS. 4M-4N, a sequential illustration of the loadingof the reservoir and engagement of the drive screw 314 to the plungerrod 310 is shown. As the plunger rod 310 fits through the clearancehole, the reservoir 306 disengages the locking tab 402 from the firstlocking tab notch 408. The reservoir alignment tab 307 (the other tab isobscured) mates with the reservoir tab opening 406. As shown in FIG. 4N,the plunger rod 310 is engaged with the drive screw 314. The locking tab402 is being engaged with the second locking tab notch 410.

In the exemplary embodiment, loading the reservoir into the pump barreland engaging the plunger rod to the drive screw includes two steps.First, aligning the locking hub alignment tabs with the hub and batteryend cap and dropping the reservoir and locking hub assembly into thepump barrel (the plunger rod being inherently aligned with the clearancehole of the locking disc). Second, rotating the locking hub untilrotation stops, i.e., the locking tab has engaged with the secondlocking tab notch. In the exemplary embodiment, and referring again toFIG. 4F, the hub and battery end cap 404 may include an loadingalignment feature 420, and the reservoir may also include a marking orother alignment feature, aligning the marking on the reservoir with theloading alignment feature 420 assures the reservoir assembly is alignedfor dropping the reservoir and locking hub assembly into the pump barreland completion of the loading steps. In the exemplary embodiment, theloading alignment feature 420 is a notch molded into the plastic of thehub and battery end cap 404. However, in other embodiments, the loadingalignment feature 420 may be a bump, raised dimple, notch of a differentshape, or a painted marking, i.e., any feature that may be utilized bythe user in loading the reservoir and locking hub assembly. Thecomplementary feature on the reservoir may be any marking, for example,a painted marking with an indication of the direction of loading, e.g.,“pump—>>”, “—▪>>”, or, in some embodiments, a simple vertical line ofany length, a dot or other symbol that may be utilized by the user inloading the reservoir and locking hub assembly. In these embodiments,these alignment features further simplify the method of loading thereservoir and locking hub assembly into the pump assembly.

Referring again to FIG. 1C, the hub and battery end cap is shownpopulated with a locking hub 108 and a battery cap 110. In thisembodiment of the pump assembly, the locking hub 108 sits flush with thepump assembly. Thus, when loading of the reservoir, once the locking hubhas been rotated such that the locking hub is flush with the pumpassembly body, loading is complete. Thus, reservoir loading isadvantageously simplified in that the alignment features assure that thereservoir, when dropped into the pump barrel, the plunger rod andreservoir alignment tabs are aligned with the locking disc and, therotation of the locking hub until the locking hub is flush with the pumpassembly assures that reservoir loaded and the plunger rod is threadedto the drive screw.

Referring now to FIG. 5A, a view of the exemplary embodiment of theplunger rod 310 and plunger 308 is shown. The plunger 308 includes twoO-rings 366. In some embodiments, the O-rings 366 and plunger 308 may beone piece and may be made from a material that provides ample sealingproperties.

Referring now to FIGS. 5B-5C, another embodiment of the reservoirassembly 502, together with the locking hub 318, is shown. In thisembodiment, the plunger seal 506 is designed to function as a doubleo-ring plunger, however, is molded as a single part. The plunger seal506 fits over the plunger 504, which, in some embodiments, is made fromplastic, and in some embodiments, is made from the same plastic as theplunger rod 310. The plunger cap 508 fits over the plunger seal 506. The

reservoir 306 and reservoir bottom 305, in some embodiments, may be asdescribed in the above described embodiments. Referring also to FIGS.5D-5E, the plunger seal 506 is shown. As shown, the top ring-likefeature of the seal is thicker than the bottom ring-like feature.However, in other embodiments, the bottom ring-like feature may be thethicker ring-like feature, and in some embodiments, both ring-likefeatures may be the same thickness. Referring also to FIG. 5F, a crosssection of the assembled plunger of the embodiments shown in FIGS. 5B-5Eis shown. The plunger seal 506 fits around the plunger 504 and theplunger cap 504 snaps over the plunger seal 506. Referring now to FIGS.5G-5P, various embodiments of the plunger seal 506 described above areshown.

As described above, the plunger rod is connected to the plunger, and ispart of the reservoir assembly. The reservoir, as discussed above,functions to hold a volume of liquid for delivery by the infusion pumpassembly. Filling the reservoir with a liquid, e.g. insulin, prior toleading the reservoir assembly into the pump assembly is preferred.Thus, in practice, a user loads the reservoir with insulin (or anotherliquid as discussed herein), attached the locking hub (in the exemplaryembodiments, although, as discussed above, in some embodiments, thelocking hub may be integrated with the reservoir) and loads thereservoir assembly with locking hub into the pump assembly.

In the exemplary embodiments, the plunger rod is designed, as shownherein, to engage with the drive screw and be driven by the drive screw.Thus, it may be difficult for some users to load the reservoir from avial of insulin as the plunger rod is designed for drive screwengagement, not necessarily for human finger engagement. Thus, in someembodiments, a filling aid may be desirable.

Referring now to FIGS. 6A-6D, an exemplary embodiment of the reservoirfilling aid 600 is shown. In this embodiment, the filling aid 600 isdesigned to engage with the threaded portion of the plunger rod 310 asdescribed above, i.e., the filling aid includes a mating thread portion602. The filling aid 600 slides onto the plunger rod 310, and as themating thread portion 602 engages with the plunger rod threads 320, thefilling aid 600 is securely fastened to the plunger rod 310. The handle604, in the exemplary embodiment, is shaped to accommodate user'sfingers and serves as pull. In practice, the user loads the reservoir bypulling back on the handle 604. Once the user has filled the reservoir,the filling aid 600 may be easily removed from the plunger rod by movingthe filling aid 600 such that the threads disengage with the plunger rodthreads. The filling aid 600, in the exemplary embodiment, is designedto have tolerances such that the plunger rod threads are not damagedduring the filling process. In various embodiments, the filling aid maybe different shapes, for example, larger, or the handle may be shapeddifferently, to accommodate those users with arthritis or other ailmentsthat may prevent them from easily utilizing the filling aid as shown. Analternate embodiment is shown in FIGS. 6E-6F. In the exemplaryembodiment, the filling aid 600 is made from plastic, however, in otherembodiments, the filling aid 600 may be made from any materials,including but not limited to, stainless steel or aluminum.

Referring now to FIGS. 6G-6I, in some embodiments, the filling aid 606may be connected to the plunger rod 301 by way of a plastic piece 608.In these embodiments, the plastic piece 608 is manufactured such thatthe filling aid 606 may be removed from the plunger rod 310 by bendingthe plastic piece, i.e., the filling aid 606 snaps off the plunger rod310. Although the filling aid 606 in these FIGS, is shown having aparticular shape, in other embodiments, the shape may be any of theother filling aid embodiments shown herein, or others that may bedesigned as discussed above. In some of the “snap-off embodiments of thefilling aid, the filling aid 606 and plastic piece 608 may be moldedwith the plunger rod 310.

Referring now to FIGS. 7A-7B, the pump assembly 100 is shown. Referringto FIGS. 1A-1B, the pump assembly 100 includes a housing, which, in theexemplary embodiment, is made from an aluminum portion, plasticportions, and rubber portions. However, in various embodiments, thematerials and the portions vary, and

include but are not limited to, rubber, aluminum, plastic, stainlesssteel, and any other suitable materials. In the exemplary embodiment,the back of the housing, shown in FIG. 1B, includes a contour.

Referring now to FIGS. 7A-7B, portions of the housing has been removed.The switch assemblies/input devices and the user interface screen havebeen removed. The pump barrel 312 is shown with a reservoir 306 inside.The battery compartment 706 is shown in FIG. 7A, and the pump assembly100 is shown without the battery compartment 706 is FIG. 7B. Variousfeatures of the battery compartment 706 are described herein. The gearbox 364 is shown assembled with the pump housing 360 in the pumpassembly 100. The hub and battery end cap 404 is shown assembled on thepump assembly 100

Referring now to FIGS. 7C-7D, a reservoir assembly 312 is shown engagedto the drive screw 314 and in contact with the strain gauge 708. Asdescribed in more detail herein, the strain gauge 708 is in contact withthe drive screw 314. The pressure measurements of the strain gauge 708are taken by an electrical contact 710. The strain gauge 708 measuresthe pressure exerted by the drive screw 314. Although the methods forsensing an occlusion are described in more detail herein, where thedrive screw 314 is unable to drive the plunger rod 310 further into thereservoir, the drive screw 314 will exert pressure onto the strain gauge708.

Referring now to FIG. 7E, an embodiment of an optical sensor is shown.The optical sensor, as described above and in more detail in U.S. PatentApplication Publication US 2004/0135078 A1, published on Jul. 15, 2004and entitled Optical Displacement Sensor for Infusion Devices, as usedin some embodiments of the infusion pump apparatus, is a sensor used todetermine whether the plunger rod 310 has moved and/or advanced andadditionally, may also determine whether the plunger rod 310 has movedand/or advanced the intended distance. Thus, in the infusion pump systemand apparatus described herein, the pump apparatus, using the occlusiondetection methods

and devices, can determine if the drive screw is unable to advance, andalso, can determine if the plunger rod has moved and the distance inwhich it has moved.

Referring now to FIGS. 8A-8D, alternate embodiments of the reservoirassembly are shown. Although the embodiments discussed and describedabove may be used in a pumping assembly, and in some embodiments, areused in the pumping assemblies shown and described herein, in otherembodiments, the pumping assembly shape and size may vary from the onesshown herein. For example, the pump assembly may be round or smaller inshape. Therefore, it may be beneficial for the reservoir assembly toaccommodate the smaller or rounded shape without having to sacrificetotal volume. Exemplary embodiments of these alternate embodimentreservoir assemblies are shown in FIGS. 8A-8C. However, it should beunderstood these are by example only. Depending on the size and shape ofthe pump assembly, the alternate embodiment reservoir assembly may belarger, smaller, or include a larger or smaller angle.

Referring now to FIG. 8A, a curved reservoir assembly 800 is shown. Inthe various embodiments, the angle indicated may have a value of greaterthan or less than 180 degrees. In one exemplary embodiment, thereservoir assembly 800 may have an angle of 150 degrees. In someembodiments, the reservoir assembly 800 may form a helical shape. Inother embodiments, the reservoir assembly 800 may be any shape desired,including having one or more portions rounded or curved, and/or one ormore portions straight or approaching straight.

Referring now to FIGS. 8B-8D, another embodiment of the alternateembodiment reservoir assembly is shown. In this embodiment, thereservoir 802 and plunger 804 assembly is shown as having a round orapproaching round shape. The reservoir 802, in some embodiments, and asshown in FIGS. 8B-8D, may be a channel in a housing 806. The reservoir802 may be cylindrical, and the ends 808, 810 of the plunger 804 may becircular, however, the plunger 804 may be flat 804 as shown. In variousembodiments, the plunger 804 may be advanced by applying pressure to theend 808 of the plunger 804by a mechanical feature (not shown), which, in some embodiments, may belocated in the center 812 of the housing 806, or in other embodiments,elsewhere in the pump assembly within engageable proximity to theplunger 804. In some embodiments, the reservoir 802 may be filled withliquid using inlet 814.

As discussed above, enclosure assembly 102 may include infusion portassembly 112 to which cannula assembly 114 may be releasably coupled. Aportion of infusion port assembly 112 and a portion of cannula assembly114 may form a medium connector assembly for releasably couplinginfusion port assembly 112 to cannula assembly 114 and effectuating thedelivery of infusible fluid 200 to user 202.

Referring to FIG. 9A, there is shown one exemplary embodiment of amedium connector assembly 900 for connecting medium carrying components(not shown) and allowing the flow of medium therebetween. Examples ofmedium carrying components may include, but are not limited to, adelivery catheter and an insulin delivery pump, a fluid supply (such asan intravenous fluid supply bag, a dialysate supply, etc.) and a pumpsupply catheter, or the like. Connector assembly 900 may include mediumconnector 902 associated with a first medium carrying component (notshown) and mating connector 904 associated with a second medium carryingcomponent.

Medium connector 902 may include passage 906 to allow for the flow ofmedium. The medium flowing between the medium carrying components, e.g.,via passage 906, may include liquids (e.g., insulin, dialysate, salinesolution, or the like), gases (e.g., air, oxygen, nitrogen, or thelike), suspensions, or the like. Further, medium connector 902 mayinclude multi-portion engagement surface 908, generally, positionedabout passage 906. Multi-portion engagement surface 908 may includefirst surface portion 910, and second surface portion 912.

As will be discussed below in greater detail, first surface portion 910of multi-portion engagement surface 908 may be configured to provide aninterference fit with corresponding sealing surface 914 of matingconnector 904. Further, second surface portion 912 of multi-portionengagement surface 908 may be configured to provide a clearance fit withcorresponding sealing surface 914 of mating connector 904. The ratio offirst surface portion 910 and second surface portion 912 may be selectedto regulate an engagement for between medium connector 902 and matingconnector 904.

For example, corresponding sealing surface 914 of mating connector 904may include a tapered surface, e.g., which may include a 6% taper (e.g.,approximately 3.4 degree included taper) of a standard Luer taperconnector (e.g., as defined by the ISO 594 standard). Of course,corresponding sealing surface 914 may include tapers other than a 6%Luer taper. Multi-portion engagement surface 908 may similarly include atapered surface, in which first surface portion 910 may have a firsttaper angle, and second surface portion 912 may have a second taperangle that is less than the first taper angle. In one particularembodiment, the second taper angle may approach zero, such that secondsurface portion 912 may be generally cylindrical (e.g., may include aslight taper, such as a draft angle to facilitate manufacture). Ofcourse, second surface portion 912 may include other, non-cylindrical,taper angles.

Continuing with the above-stated example, first surface portion 910 ofmulti-portion engagement surface 908 may include a first taper anglecorresponding to the angle of corresponding sealing surface 914 ofmating connector 904 (e.g., a 6% taper). As shown in FIG. 9B, thecorresponding taper of first surface portion 910 may provide aninterference fit with corresponding sealing surface 914 of matingconnector 904. As also shown, the second taper angle of second surfaceportion 912 may provide a clearance fit with corresponding sealingsurface 914 of mating connector 904, e.g., which may result in at leastpartial clearance 916 between second surface portion 912 andcorresponding sealing surface 914.

The contact surface area of medium connector 902 and mating connector904 may remain generally constant once first surface portion 910 hasengaged corresponding sealing surface 914. For example, as first surfaceportion 910 may be

configured to provide an interference fit with corresponding sealingsurface 914, while second surface portion 912 of multi-portionengagement surface 908 may be configured to provide a clearance fit withcorresponding sealing surface 914, only first surface portion 910 mayengage corresponding sealing surface 914.

Once first surface portion 910 engages corresponding sealing surface914, further insertion of medium connector 902 relative to matingconnector 904 may be attributable to the elastic and/or plasticdeformation force of medium connector 902 in the region of first surfaceportion 910 and/or of mating connector 904 in the region of contactbetween corresponding sealing surface 914 and first surface portion 910(e.g., as first surface portion 910 is forced into the progressivelysmaller opening provided by corresponding sealing surface 914), and thefrictional interaction between first surface portion 910 andcorresponding sealing surface 914 of mating connector 904.

As such, the ratio of first surface portion 910 and second surfaceportion 912 may be selected to regulate an engagement force betweenmedium connector 902 and mating connector 904. As discussed above,second surface portion 912 may be configured to provide a clearance fitwith corresponding sealing surface 914, and as such may not contributeto the engagement force (e.g., the insertion force per increment ofaxial insertion) between medium connector 902 and mating connector 904.Therefore, the ratio of first surface portion 910 to second surfaceportion 912 may be increased to increase the engagement force betweenmedium connector 902 and mating connector 904. Conversely, the ratio offirst surface portion 910 to second surface portion 912 may be decreasedto decrease the engagement force between medium connector 902 and matingconnector 904.

The ability to regulate the engagement force between medium connector902 and mating connector 904 (e.g., based upon the ratio of firstsurface portion 910 and second surface portion 912) may allow the use offeatures associated with medium connector 902 (and/or the firstassociated medium carrying component) and/or mating connector 904(and/or the second associated medium carrying component) which mayrequire a minimum insertion depth to be achieved within a selected rangeof insertion forces. For example, medium connector 902 may include oneor more retention features, e.g., which may facilitate a positiveengagement and/or relative position between medium connector 902 andmating connector 904. As shown in FIGS. 9A-9B, the one or more retentionfeatures may include one or more snap-fit features (e.g., cooperatingsnap-fit features 918, 920A, respectively associated with mediumconnector 902 and mating connector 904). As shown, one or more ofcooperating snap-fit features 918, 920A may be disposed on a cantileverfeature (e.g., cantilever arm 922), e.g., which may facilitateengagement/dis-engagement of cooperating snap-fit features 918, 920A.Snap-fit features 918, 920A may require a minimum insertion depth toprovide engagement therebetween. As described above, the ratio of firstsurface portion 910 and second surface portion 912 may be selected toregulate the engagement force between medium connector 902 and matingconnector 904 associated with the insertion depth necessary to provideengagement between snap-fit features 918, 920A. While regulating theengagement force between the medium connector and the mating connectorhas been described in connection with the use of retention features,this is not intended as a limitation of the present disclosure, as theability to regulate the engagement force between the medium connectorand the mating connector may equally be used for other purposes.

Referring also to FIGS. 9C and 9D, the medium connector assembly mayinclude medium connector 902 associated with a first medium carryingcomponent (not shown) and mating connector 904 associated with a secondmedium carrying component. As shown, one or more of the cooperatingsnap-fit features (e.g., cooperating snap-fit features 918, 920B) may beprovided as a feature associated with one of the mating surfaces of themedium connector assembly (e.g., snap-fit feature 920B may be formed onmember 924 defining corresponding sealing surface 914). Based upon, atleast in part,

the illustrated exemplary embodiments of FIGS. 9A-9B and 9C-9D, variousadditional/alternative arrangements may be readily understood, and arecontemplated by the present disclosure.

In addition/as an alternative to the second surface portion including asecond taper angle, the second surface portion may include one or morerecesses. For example, and referring also to FIG. 9E, the second surfaceportion may include one or more recesses including one or morelongitudinal slots (e.g., longitudinal slot 950), e.g., which may beformed in first surface portion 910. Longitudinal slot 950 may beconfigured to provide a clearance fit with cooperating sealing surface114 of mating connector 904. For example, longitudinal slot 950 mayprovide a second surface portion which may not engage cooperatingsealing surface 914 when first surface portion 910 is fully engaged withcooperating sealing surface 914 of mating connector 904. The ratio offirst surface portion 910 and the radial slots (e.g., longitudinal slot950) may be selected to regulate the engagement force between mediumconnector 902 and mating connector 904, e.g., in as much as longitudinalslot 950 may not provide a frictional engagement force with cooperatingsealing surface 914 of mating connector 904.

Referring also to FIG. 9F, additionally/alternatively the second surfaceportion may include one or more recesses that may include one or moreradial slots (e.g., radial slot 952). Similar to the above-describedlongitudinal slots (e.g., longitudinal slot 950), radial slot 952 may beconfigured to provide a clearance fit with corresponding sealing surface914 of mating connector 904. As such, the ratio of first surface portion910 and the radial slots (e.g., radial slot 952) may be selected toregulate the engagement force between medium connector 902 and matingconnector 904. For example, radial slot 952 may not provide a frictionalengagement force with cooperating sealing surface 914 of matingconnector 904.

In addition to the specifically described and depicted recesses in theform of longitudinal slots and radial slots, the one or more recessesmay include various

additional and/or alternative configurations (e.g., dimples, etc.),which maybe configured to provide a clearance fit with the cooperatingsealing surface of the mating connector. As such, the ratio of the firstsurface portion and the second surface portion (including one or morerecesses) may be selected to regulate an engagement force between themedium connector and the mating connector. Further, it will beappreciated that the number, arrangement, and character of the one ormore recesses may vary according to design criteria and preference.

While the above-described embodiments have been depicted having amulti-portion engagement surface configured as a male medium connectorportion, referring also to FIGS. 9G-9H, medium connector 902 mayadditionally/alternatively be configured as a female connector portion.For example, medium connector 902 may include a female connector portionhaving a multi-portion engagement surface including first surfaceportion 910 and second surface portion 912. As shown in FIG. 9G, themulti-portion engagement surface may include a tapered surface, in whichfirst surface portion 910 may have a first taper angle configured toprovide an interference fit with cooperating sealing surface 914 of malemating connector 904. Further, second surface portion 912 may have asecond taper angle that is greater than the first taper angle. As such,second surface portion 912 may be configured to provide a clearance fitwith cooperating sealing surface 914 of male mating connector 904.

Further, the second surface portion may include one or more recesses.For example, and referring also to FIGS. 9H-9I, the one or more recessesmay include one or more longitudinal slots (e.g., longitudinal slot950A, 950B). Similar to previously described embodiments, first surfaceportion 910 may be configured to provide an interference fit withcooperating sealing surface 914 of male mating connector 904. Further,the second surface portion, including longitudinal slot 950A, 950B, maybe configured to provide a clearance fit with cooperating sealingsurface 914 of male mating connector 904. Medium connector 902 mayinclude sealing region 954, which may not include longitudinal slots,e.g., to thereby facilitate achieving a seal between first surfaceportion 910 and cooperating sealing surface 914 of mating connector 904.

Referring also to FIG. 9J, the second surface portion may include one ormore recesses, in which the one or more recesses may include one or moreradial slots (e.g., radial slot 952). Radial slot 952 may be configuredto provide a clearance fit with cooperating sealing surface 914 of malemating connector 904.

In addition to the specifically described and depicted recesses in theform of longitudinal slots and radial slots, the one or more recessesmay include various additional and/or alternative configurations (e.g.,dimples, etc.), which may be configured to provide a clearance fit withthe cooperating sealing surface of the mating connector. As such, theratio of the first surface portion and the second surface portion(including one or more recesses) may be selected to regulate anengagement force between the medium connector and the mating connector.Further, it will be appreciated that the number, arrangement, andcharacter of the one or more recesses may vary according to designcriteria and preference.

As discussed above, infusion pump assembly 100 may include a removablecover assembly 116 configured to allow access to power supply cavity 118(shown in phantom on FIG. 2).

Referring also to FIGS. 10A-10C, power supply cavity 118 (which may beformed by a combination of removable cover assembly 116 and a portion ofenclosure assembly 102) may be configured to releasably receive primarypower supply 220. Additionally, power supply cavity 118 may beconfigured to prevent primary power supply 220 from beingreverse-polarity electrically coupled to processing logic 204 Forexample, power supply cavity 118 may be configured to prevent positiveterminal 1000 of primary power supply 220 from being electricallycoupled to negative terminal 1002 of power supply cavity 118 and/ornegative terminal 1004 of primary power supply 220 from beingelectrically coupled to positive terminal 1006 of power supply cavity118).

Configuring power supply cavity 118 to prevent primary power supply 220from being reverse-polarity electrically coupled to processing logic 204may provide various benefits. For example, the configuration may preventthe loss of power from primary power supply 220 (e.g., discharge of thebattery) where the primary power supply assembly 220 has been insertedincorrectly. In addition to functioning to not waste power, thisconfiguration may also be a safety feature to infusion pump assembly100. Infusion pump assembly 100 may rely on power for functionality. Auser may rely on infusion pump assembly 100 to provide life-sustainingtherapy, for example, by delivering insulin. Thus, preventing primarypower supply 220 from being reverse-polarity electrically coupled toprocessing logic 204 (e.g., as a result of user 202 having mistakenlyinserted primary power supply 220 incorrectly), preventing primary powersupply 220 from being reverse-polarity electrically coupled toprocessing logic 204 may allow infusion pump assembly 100 to functionfor a longer time than if the incorrectly installed primary power supply220 had been able to be reverse-polarity electrically coupled toprocessing logic 204.

Removable cover assembly 116 may be configured to allow access to powersupply cavity 118 and effectuate the installation/replacement/removal ofprimary power supply 220. As discussed above, an example of primarypower supply 220 may include but is not limited to a battery. In someembodiments, the battery may include, but is not limited to, an A, AA,AAA, or AAAA battery, and the battery may be a lithium battery oralkaline battery. The battery may, in some embodiments, be arechargeable battery.

Removable cover assembly 116 may be configured to rotatably engageenclosure assembly 102 in the direction of arrow 1008. For example,removable cover assembly 116 may include first twist lock assembly 1010(e.g., a protruding tab). Enclosure assembly 102 may include a secondtwist lock assembly 1012 (e.g., a slot) configured to releasably engagefirst twist lock assembly and effectuate the releasable

engagement of the removable cover assembly and the enclosure assembly.

While removable cover assembly 116 and enclosure assembly 102 isdescribed above as including first twist lock assembly 1010 and secondtwist lock assembly 1012, this is for illustrative purposes only and isnot intended to be a limitation of this disclosure, as otherconfigurations are possible and are considered to be within the scope ofthis disclosure. For example, one or more thread assemblies (not shown)may be utilized to effectuate the above-described rotatable engagement.

Further, while removable cover assembly 116 is described above as beingconfigured to rotatably engage enclosure assembly 102, this is forillustrative purposes only and is not intended to be a limitation ofthis disclosure, as other configurations are possible. For example,removable cover assembly 116 may be configured to slidably engageenclosure assembly 102 (in the direction of arrow 1014) using a slideassembly (not shown). Alternatively, removable cover assembly 116 may beconfigured to be pressed into enclosure assembly 102 in the direction ofarrow 1016.

Removable cover assembly 116 may include sealing assembly 1018 (e.g., ano-ring assembly) that is configured to releasably engage at least aportion of enclosure assembly 102 to form an essentially water-tightseal between removable cover assembly 116 and enclosure assembly 102.

In an embodiment in which sealing assembly 1018 includes an o-ringassembly included within removable cover assembly 116, the o-ringassembly may be sized to effectuate a watertight (or essentiallywatertight) seal with a corresponding surface of enclosure assembly 102.

Alternatively, in an embodiment in which sealing assembly 1018 includesan o-ring assembly included within enclosure assembly 102, the o-ringassembly may be sized to effectuate a watertight (or essentiallywatertight) seal with a corresponding surface of removable coverassembly 116.

Removable cover assembly 116 may include conductor assembly 1020 forelectrically coupling positive terminal 1006 of removable cover assembly116 with interior wall 120 (FIG. 1D) of power supply cavity 118. Forexample, conductor assembly 1020 may include a plurality of tabs (e.g.,tabs 1022, 1024) that may be electrically coupled to positive terminal1006 of removable cover assembly 116. Tabs 1022, 1024 may be configuredso that when removable cover assembly 116 releasably engages enclosureassembly 102, tabs 1022, 1024 may make electrical contact with interiorwall 120 of power supply cavity 118. Interior wall 120 of power supplycavity 118 may then be electrically coupled to the various componentswithin infusion pump assembly 100 that require electrical power,examples of which may include but are not limited to processing logic204,

As discussed above, the combination of removable cover assembly 116 anda portion of enclosure assembly 102 may be configured to prevent primarypower supply 220 from being reverse-polarity electrically coupled toe.g., processing logic 204. Referring also to FIG. 11, one or more ofnegative terminal 1002 and positive terminal 1006 may be configured sothat the above-described reverse polarity situation cannot occur. Forexample, removable cover assembly 116 may include insulator assembly1026 that includes recess 1028 that is sized to receive positiveterminal 1000 of primary power supply 220 and enable electrical contactwith positive terminal 1006 of removable cover assembly 116. Insulatorassembly 1026 may be constructed of an insulating material, such as PVCplastic or bakelite. Further, recess 1028 may be sized so that negativeterminal 1004 of primary power supply 220 cannot make electrical contactwith positive terminal 1006 (and may only make contact with insulator1026), thus preventing primary power supply 220 from being electricallycoupled to processing logic 204 in a reverse-polarity configuration.

Referring also to FIGS. 12A-12D, there is shown analternative-embodiment removable cover assembly 116′. Removable coverassembly 116′ may include sealing assembly 1018′ (e.g., an o-ringassembly) that is configured to releasably engage at least a portion ofenclosure assembly 102 to form an essentially water-tight seal betweenremovable cover assembly 116′ and enclosure assembly 102.

Removable cover assembly 116′ may include conductor assembly 1020′ forelectrically coupling positive terminal 1006′ of removable coverassembly 116′ with interior wall 120 (FIG. 1D) of power supply cavity118 (FIG. 1D). For example, conductor assembly 1020′ may include aplurality of tabs (e.g., tabs 1022′, 1024′) that may be electricallycoupled to positive terminal 1006′ of removable cover assembly 116′.Tabs 1022′, 1024′ may be configured so that when removable coverassembly 116′ releasably engages enclosure assembly 102, tabs 1022′,1024′ may make electrical contact with interior wall 120 of power supplycavity 118. Interior wall 120 of power supply cavity 118 may then beelectrically coupled to the various components within infusion pumpassembly 100 that require electrical power, examples of which mayinclude but are not limited to processing logic 204.

As discussed above, the combination of removable cover assembly 116′ anda portion of enclosure assembly 102 may be configured to prevent primarypower supply 220 from being reverse-polarity electrically coupled toprocessing logic 204. For example, removable cover assembly 116′ mayinclude insulator assembly 1026′ that defines recess 1028′ that is sizedto receive positive terminal 1000 (FIG. 11) of primary power supply 220(FIG. 11) and enable electrical contact with positive terminal 1006′ ofremovable cover assembly 116′. Insulator assembly 1026′, which may beconstructed of an insulating material (e.g., PVC plastic or bakelite),may be molded into and/or a portion of removable cover assembly 116′.Further, recess 1028′ may be sized so that negative terminal 1004 (FIG.11) of primary power supply 220 cannot make electrical contact withpositive terminal 1006′ (and may only make electrical contact withinsulator 1026′, thus preventing primary power supply 220 from beingelectrically coupled to processing logic 204 in a reverse-polarityconfiguration.

While power supply cavity 118 is described above as having positiveterminal 1006 positioned proximate removable cover assembly 116, this isfor illustrative purposes only and is not intended to be a limitation ofthis disclosure, as other configurations are possible and are consideredto be within the scope of this disclosure. For example, negativeterminal 1002 may be positioned proximate removable cover assembly 116.

Referring also to FIG. 13, there is shown a more-detailed diagrammaticview of processing logic 204. Processing logic 204 may include one ormore circuit partitioning components 1300, 1302 configured to divideprocessing logic 204 into primary processing logic 1304 and backupprocessing logic 1306. Examples of one or more circuit partitioningcomponents 1300, 1302 may include but are not limited to diode assembly1300 and current limiting assembly 1302.

Diode assembly 1300 may be configured to allow primary power supply 220to charge backup power supply 1308 included within backup processinglogic 1306, while prohibiting backup power supply 1308 from providingbackup electrical energy 1310 to primary processing logic 1304 in theevent that some form of failure prevents primary electrical energy 1312from providing primary processing logic 1304. An example of backup powersupply 1308 may include but is not limited to a super capacitorassembly. An example of such a super capacitor assembly may include butis not limited to an electric double-layer capacitor manufactured byElna Co. Ltd. of Yokohama, Japan.

Current limiting assembly 1302 may be configured to limit the amount ofprimary electrical energy 1312 available to charge backup power supply1308. Specifically, as primary power supply 220 may be configured tocharge backup power supply 1308, the amount of current available fromprimary power supply 220 may be limited to e.g., avoid depriving primaryprocessing logic 1304 of a requisite portion of primary electricalenergy 1312.

Primary processing logic 1304 may include primary microprocessor 1314and voltage booster circuit 1316. An example of primary microprocessor1314 may include but is not limited to a H8S/2000 manufactured byRenesas Technology America Inc. of San Jose, Calif. Voltage boostercircuit 1316 may be configured to increase the voltage potential ofprimary electrical energy 1312 provided by primary power supply 220 to alevel sufficient to power primary microprocessor 1314. An example ofvoltage booster circuit 1316 may include but is not limited to a LTC3421manufactured by Linear Technology of Milpitas, Calif.

Current limiting assembly 1302 may be configured to limit the amount ofcurrent available to charge backup power supply 1308 during the power-upof primary microprocessor 1314. Specifically and for illustrativepurposes, current limiting assembly 1302 may be controlled by primarymicroprocessor 1314 and current limiting assembly 1302 may be disabled(i.e., provide no charging current to backup power supply 1308) untilafter primary microprocessor 1314 is fully powered up. Upon primarymicroprocessor 1314 being fully powered up, primary microprocessor 1314may now enable current limiting assembly 1302, thus providing chargingcurrent to backup power supply 1308. Alternatively and upon beinginitially energized, current limiting assembly 1302 may be configured toprohibit the flow of charging current to backup power supply 1308 for atime sufficient to allow for the powering up of primary microprocessor1314.

Backup processing logic 1306 may include backup power supply 1308 andsafety microprocessor 1318. An example of safety microprocessor 1318 mayinclude but is not limited to a MSP430 manufactured by Texas Instrumentsof Dallas, Tex.

Primary power supply 220 may be configured to provide primary electricalenergy 1312 to at least a portion of processing logic 204. Specificallyand during normal operation of infusion pump assembly 100, primary powersupply 220 may be configured to provide primary electrical energy 1312to all of processing logic 204 (including the various components ofprimary processing logic 1304 and backup processing logic 1306), as wellas various subsystems included within infusion pump assembly 100.

Examples of such subsystems may include but are not limited to memorysystem 206, input system 208, display system 104, vibration system 210,audio system 212, motor assembly 214, force sensor 216, and displacementdetection device 218.

Backup power supply 1308 may be configured to provide backup electricalenergy 1310 to the at least a portion of processing logic 204 in theevent that primary power supply 220 fails to provide primary electricalenergy 1312 to at least a portion of processing logic 204. Specifically,in the event that primary power supply 220 fails and, therefore, can nolonger provide primary electrical energy 1312 to processing logic 204,backup power supply 1308 may be configured to provide backup electricalenergy 1310 to backup processing logic 1306.

For illustrative purposes only, assume that infusion pump assembly 100is operating normally and primary power supply 220 is providing primaryelectrical energy 1312 to processing logic 204. As discussed above,voltage booster circuit 1316 may increase the voltage potential ofprimary electrical energy 1312 to a level sufficient to power primarymicroprocessor 1314, wherein voltage booster circuit 1316 and primarymicroprocessor 1314 are both included within primary processing logic1304.

Further, diode assembly 1300 may allow a portion of primary electricalenergy 1312 to enter backup processing logic 1306, thus enabling theoperation of safety microprocessor 1318 and the charging of backup powersupply 1308. As discussed above an example of backup power supply 1308may include but is not limited to a super capacitor. As discussed above,current limiting assembly 1302 may limit the quantity of currentprovided by primary power supply 220 to backup processing logic 1306,thus preventing the diversion of too large a portion of primaryelectrical energy 1312 from primary processing logic 1304 to backupprocessing logic 1306.

Accordingly, in addition to powering safety microprocessor 1318, primarypower supply 220 may charge backup power supply 1308. In a preferredembodiment, backup power supply 1308 is a 0.33 farad super capacitor.

Safety microprocessor 1318 may monitor the status of primary powersupply 220 by monitoring (via conductor 1320) the voltage potentialpresent at the input of voltage booster circuit 1316. Alternatively,safety microprocessor 1318 may monitor the status of primary powersupply 220 by e.g. monitoring the voltage potential present at theoutput of voltage booster circuit 1316. Further still, safetymicroprocessor 1318 and primary microprocessor 1314 may beelectrically-coupled via e.g. conductor 1322 and primary microprocessor1314 may be configured to continuously provide a “beacon” signal tosafety microprocessor 1318. Conductor 1322 may include isolation circuit1324 (e.g., one or more diodes assemblies) to electrically isolatesafety microprocessor 1318 and primary microprocessor 1314. Accordingly,provided safety microprocessor 1318 continues to receive the “beacon”signal from primary microprocessor 1314, primary microprocessor 1314 isfunctioning and, therefore, being properly powered by primary powersupply 220. In the event that safety microprocessor 1318 fails toreceive the “beacon” signal from primary microprocessor 1314, an alarmsequence maybe initiated.

Further still, safety microprocessor 1318 may be configured tocontinuously provide a “beacon” signal to primary microprocessor 1314.Accordingly, provided primary microprocessor 1314 continues to receivethe “beacon” signal from safety microprocessor 1318, safetymicroprocessor 1318 is functioning and, therefore, being properlypowered by backup power supply 1308. In the event that primarymicroprocessor 1314 fails to receive the “beacon” signal from safetymicroprocessor 1318, an alarm sequence may be initiated.

As used in this disclosure, a “beacon” signal may be considered an eventthat is performed by primary microprocessor 1314 (and/or safetymicroprocessor 1318) solely for the purpose of making the presence ofprimary microprocessor 1314 (and/or safety microprocessor 1318) known.Additionally/alternatively, the “beacon” signal may be considered anevent that is performed by primary microprocessor 1314 (and/or safetymicroprocessor 1318) for the purpose of performing a task, wherein theexecution

of this event is monitored by safety microprocessor 1318 (and/or primarymicroprocessor 1314) to confirm the presence of primary microprocessor1314 (and/or safety microprocessor 1318).

Assume for illustrative purposes that primary power supply 220 fails.For example, assume that primary power supply 220 physically fails (asopposed to simply becoming discharged). Examples of such a failure mayinclude but are not limited to the failing of a cell (not shown) withinprimary power supply 220 and the failing of a conductor (e.g., one ormore of conductors 1320, 1326) that electrically-couples primary powersupply 220 to processing logic 204. Accordingly, in the event of such afailure, primary power supply 220 may no longer provide primaryelectrical energy 1312 to processing logic 204.

However, when such a failure of primary power supply 220 occurs, thevoltage potential present at the output of voltage booster circuit 1316and the voltage potential present at the input of voltage boostercircuit 1316 may be reduced to zero. Since safety microprocessor 1318may monitor (as discussed above) one or more of these voltagepotentials, safety microprocessor 1318 may be knowledgeable that primarypower supply 220 has failed.

Further, when such a failure of primary power supply 220 occurs, primarymicroprocessor 1314 will no longer be powered and, therefore, primarymicroprocessor 1314 will no longer produce the above-described “beacon”signals. Since safety microprocessor 1318 monitors the above-described“beacon” signals, safety microprocessor 1318 may be knowledgeable thatprimary power supply 220 has failed.

As discussed above, in the event of such a failure of primary powersupply 220, as diode assembly 1300 is reversed-biased, backup powersupply 1308 may not provide backup electrical energy 1310 to primaryprocessing logic 1304. Accordingly, primary processing logic 1304 willno longer function.

Upon sensing the failure of primary power supply 220, safetymicroprocessor 1318 may initiate an alarm sequence that may result inaudio system 212 being energized. Audio system 212 may be controllableby both safety microprocessor 1318 and primary microprocessor 1314.Alternatively, a separate audio system may be used for each of safetymicroprocessor 1318 and primary microprocessor 1314. An example of audiosystem 212 may include but is not limited to a Piezo electric diaphragm,an example of which may include but is not limited to a 7BB-15-6manufactured by Murata of Kyoto, Japan.

Audio system 212 may further include an RS232 line driver circuit 1330,such as a MAX3319/MAX3221 manufactured by Maxim Integrated Products ofSunnyvale, Calif. One or more or primary microprocessor 1314 and safetymicroprocessor 1318 may be configured to provide an alarm control signal(e.g., a square wave; not shown) to RS232 line driver circuit 1330 togenerate an alarm output signal (not shown) that may be provided to andmay drive the above-described Piezo electric diaphragm.

The alarm sequence initiated by safety microprocessor 1318 is intendedto inform user 202 of the failure of primary power supply 220 so thatuser 202 may take the appropriate action (e.g. seeking an alternativemeans to have their therapy performed and/or having infusion pumpassembly 100 repaired/replaced). Backup power supply 1308 may be sizedso that safety microprocessor 1318 and audio system 212 may continue tofunction for up to fifteen minutes or more after the failure of primarypower supply 220 (i.e., depending on design specifications).

The alarm sequence initiated by safety microprocessor 1318 and/orprimary microprocessor 1314 may be an “escalating” alarm sequence. Forexample, at first a discrete “vibrating” alarm may be initiated (viavibration system 210). In the event that this “vibrating” alarm is notacknowledged within a defined period of time (e.g., one minute), a lowvolume audible alarm may be initiated. In the event that this low volumealarm is not acknowledged within a defined period of time (e.g., oneminute), a medium volume audible alarm may be initiated. In the eventthat this medium volume alarm is

not acknowledged within a defined period of time (e.g., one minute), ahigh volume audible alarm may be initiated. The escalating alarmsequence may provide a notification to user 202, in which thenotification may be discrete or less disruptive at the onset. Theinitially discrete or less disruptive notification may be advantageousas user 202 may experience minimal disruption. However, in the eventthat user 202 does not acknowledge the alarm, the escalating nature ofthe alarm may provide for additional layers of safety to user 202.Additionally, in a case of audio system 212 error, or vibration system210 error, the escalating alarm sequence, which may include bothvibration and audio alarms, may insure that user 202 may be notifiedregardless of whether both systems 210, 212 are functioning.

Audio system 212, in some embodiments, may be configured to perform aself test upon power up. For example, upon infusion pump assembly 100being initially powered up, audio system 212 may provide a “beep-type”signal to each sound generating device included within audio system 212.In the event that user 202 does not hear these “beep-type” signal(s),user 202 may take the appropriate action (e.g. seeking an alternativemeans to have their therapy performed and/or having infusion pumpassembly 100 repaired/replaced). As discussed above, audio system 212may be controllable by safety microprocessor 1318 and/or primarymicroprocessor 1314. Accordingly, when performing the above-describedself test upon power up, safety microprocessor 1318 and/or primarymicroprocessor 1314 may control the above-described self test. Thisfeature may provide for additional safety to user 202, as user 202 maybe alerted to a system error earlier than may otherwise be the case.Thus, a method may be provided to notify the user early of systemerrors. Also, the system may otherwise not be aware of an error in audiosystem 212, thus, this feature provides for identification of a failureby user 202 that may otherwise go undetected.

During the failure of primary power supply 220, safety microprocessor1318 may continue to monitor the voltage potential present at the outputof voltage

booster circuit 1316 and/or the voltage potential present at the inputof voltage booster circuit 1316. Additionally, safety microprocessor1318 may continue to monitor for the presence of the above-described“beacon” signals. Accordingly, in the event that the failure of primarypower supply 220 was a temporary event (e.g. primary power supply 220 isan out-of-date battery and is being replaced with a new battery), safetymicroprocessor 1318 may be knowledgeable when primary power supply 220is once again functioning properly.

Upon primary power supply 220 once again functioning properly, diodeassembly 1300 and current limiting assembly 1302 may allow a portion ofprimary electrical energy 1312 produced by primary power supply 220 torecharge backup power supply 1308.

Additionally, safety microprocessor 1318 and primary microprocessor 1314may each maintain a real-time clock, so that the various doses ofinfusible fluid may be dispensed at the appropriate time of day. Asprimary microprocessor 1314 was not functioning during the failure ofprimary power supply 220, the real-time clock maintained within primarymicroprocessor 1314 may no longer be accurate. Accordingly, thereal-time clock maintained within safety microprocessor 1318 may be usedto reset the real-time clock maintained within primary microprocessor1314.

In order to further enhance the reliability and safety of infusion pumpassembly 100, primary microprocessor 1314 and safety microprocessor 1318may each execute applications written in different programminglanguages. For example, primary microprocessor 1314 may be configured toexecute one or more primary applications written in a first computerlanguage, while safety microprocessor 1318 may be configured to executeone or more safety applications written in a second computer language.

Examples of the first computer language in which the primaryapplications are written may include but are not limited to Ada, Basic,Cobol, C, C++, C#, Fortran,

Visual Assembler, Visual Basic, Visual J++, Java, and Java Scriptlanguages. In a preferred embodiment, the first computer language inwhich the primary applications (executed on primary microprocessor 1314)are written is the C++ computer language.

Examples of the second computer language in which the safetyapplications are written may include but are not limited to Ada, Basic,Cobol, C, C++, C#, Fortran, Visual Assembler, Visual Basic, Visual J++,Java, and Java Script languages. In a preferred embodiment, the secondcomputer language in which the safety applications (executed on safetymicroprocessor 1318) are written is the C computer language.

Further, assuming that primary microprocessor 1314 and safetymicroprocessor 1318 are different types of microprocessors and,therefore, use different compilers; the compiled code associated withthe primary applications executed by primary microprocessor 1314 and thesafety applications executed on safety microprocessor 1318 may bedifferent (regardless of the whether the primary applications and thesafety applications were written in the same computer language.

Examples of the one or more primary applications written in the firstcomputer language and executable on primary microprocessor 1314 mayinclude but are not limited to an operating system (e.g., Linux™, Unix™,Windows CE™), an executive loop and various software applications.Further, examples of the one or more safety applications written in thesecond computer language and executable on safety microprocessor 1318may include but are not limited to an operating system (e.g., Linux™,Unix™, Windows CE™), an executive loop and various softwareapplications.

Accordingly, primary processing logic 1304 and backup processing logic1306 may each be configured as a separate stand-alone autonomouscomputing device. Therefore, primary microprocessor 1314 included withinprimary processing logic 1304 may execute a first operating system (e.g.Linux™) and safety microprocessor 1318 included within backup processinglogic 1306 may execute an executive loop.

Additionally, primary microprocessor 1314 included within primaryprocessing logic 1304 may execute one or more software applications(e.g. graphical user interface applications, scheduling applications,control applications, telemetry applications) executable within (in thisexample) a Linux™ operating system. Further, safety microprocessor 1318included within backup processing logic 1306 may execute one or moresoftware applications (e.g. graphical user interface applications,scheduling applications, control applications, telemetry applications)executable within (in this example) the executive loop.

By utilizing diverse computer languages and/or diverse operatingsystems, infusion pump assembly may be less susceptible to e.g.computer-language bugs, operating-system bugs, and/or computer viruses.

One or more of primary microprocessor 1314 (included within primaryprocessing logic 1304 of processing logic 204) and safety microprocessor1318 (included within backup processing logic 1306 of processing logic204) may execute confirmation process 234 (FIG. 2). As will be discussedbelow in greater detail, confirmation process 234 may be configured toprocess a command received on a first microprocessor (e.g., primarymicroprocessor 1314) so that the command may be confirmed by a secondmicroprocessor (e.g., safety microprocessor 1318).

The instruction sets and subroutines of confirmation process 234, whichmay be stored on a storage device (e.g., memory system 208) accessibleby processing logic 204, may be executed by one or more processors(e.g., primary microprocessor 1314 and/or safety microprocessor 1318)and one or more memory architectures (e.g., memory system 208) includedwithin infusion pump assembly 100. Examples of memory system 208 mayinclude but are not limited to: a random access memory; a read-onlymemory; and a flash memory.

Referring also to FIG. 14, confirmation process 234 may receive 1400, ona first microprocessor executing one or more applications written in afirst computer language, an initial command processable by the one ormore applications written in the first computer language. For exampleand as discussed above, primary microprocessor 1314 (included withinprimary processing logic 1304) may be executing the Linux™ operatingsystem. Assuming that user 202 wishes to have a 0.50 mL dose ofinfusible fluid 200 dispensed by infusion pump assembly 100, user 202may select (via input system 208 and display system 104) the appropriatecommands to have the 0.50 mL dose dispensed. Accordingly, primarymicroprocessor 1314 may receive 1400 a corresponding command (e.g.,command 1332) to dispense 0.50 mL of infusible fluid 200.

As discussed above, safety microprocessor 1318 (included within backupprocessing logic 1306) may be executing the executive loop. Accordingly,command 1332 may not be provided to safety microprocessor 1318 in itsnative form, as safety microprocessor 1318 may not be capable ofprocessing command 1332, due to safety microprocessor 1318 executing theexecutive loop and primary microprocessor 1314 executing the Linux™operating system.

Accordingly, confirmation process 234 may convert 1402 initial command1332 into a modified command (e.g., command 1334) that may beprocessable by e.g., safety microprocessor 1318 (included within backupprocessing logic 1306) that may be executing the executive loop. Forexample, confirmation process 234 may convert 1402 initial command 1332into modified command 1334 that is transmittable via a communicationprotocol (not shown) that effectuates the communication of primarymicroprocessor 1314 and safety microprocessor 1318. Once command 1332 isconverted 1402 into modified command 1334, modified command 1334 may beprovided 1404 to e.g., safety microprocessor 1318 (included withinbackup processing logic 1306) that may be executing e.g., the executiveloop.

Once received by e.g., safety microprocessor 1318 (included withinbackup processing logic 1306), safety microprocessor 1318 may processmodified command 1334 and provide (via e.g., display system 104) avisual confirmation to user 202. Prior to processing modified command1334, confirmation process 234 may convert modified command 1334 into anative command (not shown) processable by safety microprocessor 1318.For example, upon receiving modified command 1334, safety microprocessor1318 may process received modified command 1334 to render (on displaysystem 104) a visual confirmation.

Upon processing modified command 1334, confirmation process 234 mayrender on display system 104 a message that states e.g., “Dispense 0.50U Dose?”. Upon reading this message, user 202 may either authorize thedispensing of the 0.50 mL dose or cancel the dispensing of the 0.50 mLdose. Accordingly, if user 202 authorizes the dispensing of the 0.50 mLdose of infusible fluid 200, the accuracy of initial command 1332 andmodified command 1334 are both confirmed. However, in the event thate.g., the message rendered by confirmation process 234 is incorrect(e.g., “Dispense 1.50 U Dose?”), the conversion 1402 of initial command1332 to modified command 132 has failed. Accordingly, primarymicroprocessor 1314 (and/or the applications being executed on primarymicroprocessor 1314) and/or safety microprocessor 1318 (and/or theapplications being executed on safety microprocessor 1318) may bemalfunctioning. Accordingly, user 202 may need to seek an alternativemeans to having their therapy performed and/or have infusion pumpassembly 100 serviced.

As discussed above, infusion pump assembly 100 may be configured todeliver infusible fluid 200 to user 202. Infusible fluid 200 may bedelivered to user 202 via one or more different infusion event types.For example, infusion pump assembly 100 may deliver infusible fluid 200via may a sequential, multi-part, infusion event (that may include aplurality of discrete infusion events) and/or a one-time infusion event.

Examples of such a sequential, multi-part, infusion event may includebut are not limited to a basal infusion event and an extended-bolusinfusion event. As is known in the art, a basal infusion event refers tothe constant flow of a small quantity of infusible fluid 200. However,as such an infusion methodology is impractical/undesirable

for an infusion pump assembly, when administered by such an infusionpump assembly, a basal infusion event may refer to the repeatedinjection of small (e.g. 0.05 unit) quantities of infusible fluid 200 ata predefined interval (e.g. every three minutes) that is repeated. Thequantity of infusible fluid 200 delivered during each interval may beidentical or may vary from interval to interval. Further, the timeinterval between each delivery of infusible fluid 200 may be identicalor may vary from interval to interval. Further, the basal infusion ratesmay be pre-programmed time-frames, e.g., a rate of 0.50 units per hourfrom 6 am-3 pm; a rate of 0.40 units per hour from 3 pm-10 pm; and arate of 0.35 units per hour from 10 pm-6 am. However, similarly, thebasal rate may be 0.025 units per hour, and may not change according topre-programmed time-frames. The basal rates may be repeatedregularly/daily until otherwise changed.

Further and as is known in the art, and extended-bolus infusion eventmay refer to the repeated injection of small (e.g. 0.025 unit)quantities of infusible fluid 200 at a predefined interval (e.g. everythree minutes) that is repeated for a defined number of intervals (e.g.,three intervals) or for a defined period of time (e.g., one hour). Anextended-bolus infusion event may occur simultaneously with a basalinfusion event.

In contrast, as in known in the art, a normal bolus infusion eventrefers to a one-time infusion of infusible fluid 200. The volume of theinfusible fluid 200 delivered in a bolus infusion event may berequested, and infusion pump assembly 100 may deliver the requestedvolume of infusible fluid 200 for the bolus infusion event at apredetermined rate (e.g., as quickly as the infusion pump assembly candeliver). However, the infusion pump assembly may deliver a normal bolusat a slower rate where the normal bolus volume is greater than apre-programmed threshold.

Referring also to FIGS. 15-16, assume for illustrative purposes onlythat user 202 configures infusion pump assembly 100 to administer abasal dose (e.g. 0.05 units) of infusible fluid 200 every three minutes.As discussed above, infusion pump assembly 100 may include input system208 and display system 104. Accordingly, user 202 may utilize inputsystem 208 to define a basal infusion event for infusible fluid 200(e.g., 1.00 units per hour), which may be confirmed via display system104. While, in this example, the basal infusion event is described as1.00 units per hour, this is for illustrative purposes only and is notintended to be a limitation of this disclosure, as either or both of theunit quantity and time period may be adjusted upward or downward.Infusion pump assembly 100 may then determine an infusion schedule basedupon the basal infusion event defined; and may administer 100 infusiblefluid 200. For example, infusion pump assembly 100 may deliver 0.05units of infusible fluid 200 every three minutes, resulting in thedelivery of the basal dose of infusible fluid 200 defined by the user(i.e., 1.00 units per hour).

Once defined and/or confirmed, fluid delivery process 236 may administer1500 the sequential, multi-part, infusion event (e.g., 0.05 units ofinfusible fluid 200 every three minutes). Accordingly, whileadministering 1500 the sequential, multi-part, infusion event, infusionpump assembly 100: may infuse a first 0.05 unit dose 1600 of infusiblefluid 200 at t=0:00 (i.e., a first discrete infusion event), may infusea second 0.05 unit dose 1602 of infusible fluid 200 at t=3:00 (i.e., asecond discrete infusion event); may infuse a third 0.05 unit dose 1604of infusible fluid 200 at t=6:00 (i.e., a third discrete infusionevent); may infuse a fourth 0.05 unit dose 1606 of infusible fluid 200at t=9:00 (i.e., a fourth discrete infusion event); and may infuse afifth 0.05 unit dose 1608 of infusible fluid 200 at t=12:00 (i.e., afifth discrete infusion event). As discussed above, this pattern ofinfusing 0.05 unit doses of infusible fluid 200 every three minutes maybe repeated indefinitely in this example, as this is an illustrativeexample of a basal infusion event.

Further, assume for illustrative purposes that infusible fluid 200 isinsulin and sometime after the first 0.05 unit dose 1600 of infusiblefluid 200 is administered 1500 by fluid delivery process 236 (but beforethe second 0.05 unit dose 1602 of infusible fluid 200 is administered1500 by fluid delivery process 236), user 202 checks their blood glucoselevel and realizes that their blood glucose level is running a littlehigher than normal. Accordingly, user 202 may define an extended bolusinfusion event via fluid delivery process 236. An extended bolusinfusion event may refer to the continuous infusion of a definedquantity of infusible fluid 200 over a finite period of time. However,as such an infusion methodology is impractical/undesirable for aninfusion pump assembly, when administered by such an infusion pumpassembly, an extended bolus infusion event may refer to the infusion ofadditional small doses of infusible fluid 200 over a finite period oftime.

Accordingly, user 202 may utilize input system 208 to define an extendedbolus infusion event for infusible fluid 200 (e.g., 0.20 units over thenext six minutes), which may be confirmed via display system 104. While,in this example, the extended bolus infusion event is described as 0.20units over the next six minutes, this is for illustrative purposes onlyand is not intended to be a limitation of this disclosure, as either orboth of the unit quantity and total time interval may be adjusted upwardor downward. Once defined and/or confirmed, fluid delivery process 236may determine an infusion schedule based upon the extended bolusinfusion event defined; and may administer 1500 infusible fluid 200. Forexample, infusion pump assembly 100 may deliver 0.10 units of infusiblefluid 200 every three minutes for the next two interval cycles (or sixminutes), resulting in the delivery of the extended bolus dose ofinfusible fluid 200 defined by the user (i.e., 0.20 units over the nextsix minutes).

Accordingly, while administering 1500 the second, sequential,multi-part, infusion event, infusion pump assembly 100 may infuse afirst 0.10 unit dose 1610 of infusible fluid 200 at t=3:00 (e.g., afteradministering the second 0.05 unit dose 1602 of infusible fluid 200).Infusion pump assembly 100 may also infuse a second 0.10 unit dose 1612of infusible fluid 200 at t=6:00 (e.g., after administering the third0.05 unit dose 1604 of infusible fluid 200).

Assume for illustrative purposes only that after user 202 programsinfusion pump assembly 100 to administer 1500 the first sequential,multi-part, infusion event (i.e., 0.05 units infused every three minuteinterval repeated continuously) and administer 1500 the secondsequential, multi-part, infusion event (i.e., 0.10 units infused everythree minute interval for two intervals), user 202 decides to eat a verylarge meal. Predicting that their blood glucose level might increaseconsiderably, user 202 may program infusion pump assembly 100 (via inputsystem 208 and/or display system 104) to administer 1502 a one-timeinfusion event. An example of such a one-time infusion event may includebut is not limited to a normal bolus infusion event. As is known in theart, a normal bolus infusion event refers to a one-time infusion ofinfusible fluid 200.

For illustrative purposes only, assume that user 202 wishes to haveinfusion pump assembly 100 administer 1502 a bolus dose of thirty-sixunits of infusible fluid 200. Fluid delivery process 236 may monitor thevarious infusion events being administered by fluid delivery process 236to determine 1504 whether a one-time infusion event is available to beadministered. If 1504 a one-time infusion event is available foradministration 1502, fluid delivery process 236 may delay 1506 theadministration of at least a portion of the sequential, multi-part,infusion event.

Continuing with the above-stated example, once user 202 completes theprogramming of fluid delivery process 236 to deliver one-time infusionevent 1614 (i.e., the thirty-six unit bolus dose of infusible fluid200), upon fluid delivery process 236 determining 1504 that the one-timeinfusion event is available for administration 1502, fluid deliveryprocess 236 may delay 1506 the administration 1500 of each sequential,multi-part infusion event and administer 1502 the available one-timeinfusion event.

Specifically and as discussed above, prior to user 202 programming fluiddelivery process 236 to deliver one-time infusion event 1614, infusiondelivery process 236 was administering 1500 a first sequential,multi-part, infusion event (i.e., 0.05 units infused every three minuteinterval repeated continuously) and administering 1500 a secondsequential, multi-part, infusion event (i.e., 0.10 units infused everythree minute interval for two intervals).

For illustrative purposes only, the first sequential, multi-part,infusion event may be represented within FIG. 16 as 0.05 unit dose 1600@ t=0:00, 0.05 unit dose 1602 @ t=3:00, 0.05 unit dose 1604 @ t=6:00,0.05 unit dose 1606 @ t=9:00, and 0.05 unit dose 1608 @ t=12:00. As thefirst sequential, multi-part, infusion event is described above is abasal infusion event, infusion pump assembly 100 (in conjunction withfluid delivery process 236) may continue to infuse 0.05 unit doses ofinfusible fluid 200 at three minute intervals indefinitely (i.e., untilthe procedure is cancelled by user 202).

Further and for illustrative purposes only, the second sequential,multipart, infusion event may be represented within FIG. 16 as 0.10 unitdose 1610 @ t=3:00 and 0.10 unit dose 1612 @ t=6:00. As the secondsequential, multi-part, infusion event is described above as an extendedbolus infusion event, infusion pump assembly 100 (in conjunction withfluid delivery process 236) may continue to infuse 0.10 unit doses ofinfusible fluid 200 at three minute intervals for exactly two intervals(i.e., the number of intervals defined by user 202).

Continuing with the above-stated example, upon fluid delivery process236 determining 1504 that the thirty-six unit normal bolus dose ofinfusible fluid 200 (i.e., one-time infusion event 1614) is availablefor administration 1502, fluid delivery process 236 may delay 1506 theadministration 1500 of each sequential, multi-part infusion event andmay start administering 1502 one-time infusion event 1614 that isavailable for administration.

Accordingly and for illustrative purposes only, assume that uponcompletion of the programming of infusion pump assembly 100 to deliverthe thirty-six unit normal bolus does of infusible fluid 200 (i.e., theone-time infusion event), fluid delivery process begins administering1502 one-time infusion event 1614. Being that one-time infusion event1614 is comparatively large, it may take longer than three minutes(i.e., the time interval between individual infused doses of thesequential, multi-part, infusion events) to administer and, therefore,one or more of the individual infused doses of the sequential,multi-part, infusion events may need to be delayed.

Specifically, assume that it will take infusion pump assembly 100greater than six minutes to infuse thirty-six units of infusible fluid200. Accordingly, fluid delivery process 236 may delay 0.05 unit dose1602 (i.e., scheduled to be infused @ t=3:00), 0.05 unit dose 1604(i.e., scheduled to be infused @ t=6:00), and 0.05 unit dose 1606 (i.e.,scheduled to be infused @ t=9:00) until after one-time infusion event1614 (i.e., the thirty-six unit normal bolus dose of infusible fluid200) is completely administered. Further, fluid delivery process 236 maydelay 0.10 unit dose 1610 (i.e., scheduled to be infused @ t=3:00 and0.10 unit dose 1612 (i.e., scheduled to be infused @ t=6:00) until afterone-time infusion event 1614.

Once administration 1502 of one-time infusion event 1614 is completed byfluid delivery process 236, any discrete infusion events included withinthe sequential, multi-part, infusion event that were delayed may beadministered 1500 by fluid delivery process 236.

Accordingly, once one-time infusion event 1614 (i.e., the thirty-sixunit normal bolus dose of infusible fluid 200) is completelyadministered 1502, fluid delivery process 236 may administer 1500 0.05unit dose 1602, 0.05 unit dose 1604, 0.05 unit dose 1606, 0.10 unit dose1610, and 0.10 unit dose 1612.

While fluid delivery process 236 is shown to administer 1500 0.05 unitdose 1602, then 0.10 unit dose 1610, then 0.05 unit dose 1604, then 0.10unit dose 1612, and then 0.05 unit dose 1606, this is for illustrativepurposes only and is not intended to be a limitation of this disclosure,as other configurations are possible and are considered to be within thescope of this disclosure. For example, upon fluid delivery process 236completing the administration 1502 of one-time infusion event 1614(i.e., the thirty-six unit normal bolus dose of infusible fluid 200),fluid delivery process 236 may administer 1500 all of the delayeddiscrete infusion events associated with the first sequential,multi-part infusion event (i.e., namely 0.05 unit dose 1602, 0.05 unitdose 1604, and 0.05 unit dose 1606. Fluid delivery process 236 may thenadminister 1500 all of the delayed discrete infusion events associatedwith the second sequential, multi-part infusion event (i.e., 0.10 unitdose 1610, and 0.10 unit dose 1612).

While one-time infusion event 1614 (i.e., the thirty-six unit normalbolus dose of infusible fluid 200) is shown as being infused beginningat t=3:00, this is for illustrative purposes only and is not intended tobe a limitation of this disclosure. Specifically, fluid delivery process236 may not need to begin infusing one-time infusion event 1614 at oneof the three-minute intervals (e.g., t=0:00, t=3:00, t=6:00, t=9:00, ort=12:00) and may begin administering 1502 one-time infusion event 1614at any time.

While each discrete infusion event (e.g., 0.05 unit dose 1602, 0.05 unitdose 1604, 0.05 unit dose 1606, 0.10 unit dose 1610, and 0.10 unit dose1612) and onetime infusion event 1614 are shown as being a single event,this is for illustrative purposes only and is not intended to be alimitation of this disclosure. Specifically, at least one of theplurality of discrete infusion events e.g., 0.05 unit dose 1602, 0.05unit dose 1604, 0.05 unit dose 1606, 0.10 unit dose 1610, and 0.10 unitdose 1612) may include a plurality of discrete infusion sub-events.Further, one-time infusion event 1614 may include a plurality ofone-time infusion sub-events.

Referring also to FIG. 17 and for illustrative purposes, 0.05 unit dose1602 is shown to include ten discrete infusion sub-events (e.g.,infusion sub-events 1700 i_io), wherein a 0.005 unit dose of infusiblefluid 200 is infused during each of the ten discrete infusionsub-events. Additionally, 0.10 unit dose 1610 is shown to include tendiscrete infusion sub-events (e.g., infusion sub-events 1702 MO),wherein a 0.01 unit dose of infusible fluid 200 is delivered during eachof the ten discrete infusion sub-events. Further, one-time infusionevent 1614 may include e.g., three-hundred-sixty one-time infusionsub-events (not shown), wherein a 0.1 unit dose of infusible fluid 200is delivered during each of the three-hundred-sixty one-time infusionsub-events. The number of sub-events defined above and the quantity ofinfusible fluid 200 delivered during each sub-event is solely forillustrative purposes only and is not intended to be a limitation ofthis disclosure, as the number of sub-events and/or the quantity ofinfusible fluid 200 delivered during each sub-event may be increased ordecreased depending upon e.g., the design criteria of infusion pumpassembly 100 and/or the implementation of fluid delivery process 236.

Before, after, or in between the above-described infusion sub-events,infusion pump assembly 100 may confirm the proper operation of infusionpump assembly 100 through the use of e.g., force sensor 216 (i.e., whichmay determine the occurrence of an occlusion) and displacement detectiondevice 218 (i.e., which may determine the occurrence of a mechanicalfailure).

As discussed above, during operation of infusion pump assembly 100,infusible fluid 200 may be delivered to user 202 in accordance with e.g.a defined delivery schedule. For illustrative purposes only, assume thatinfusion pump assembly 100 is configured to provide 0.10 mL of infusiblefluid 200 to user 202 every three minutes. Accordingly, every threeminutes, processing logic 204 may provide the appropriate drive signalsto motor assembly 214 to allow motor assembly 214 to rotate lead screwassembly 42 the appropriate amount so that partial nut assembly 40 (andtherefore plunger assembly 224) may be displaced the appropriate amountin the direction of arrow 230 so that 0.10 mL of infusible fluid 200 areprovided to user 202 (via cannula 38).

Processing logic 204 may execute occlusion detection process 238, andocclusion detection process 238 may be configured to monitor one or moreevents that are occurring within infusion pump assembly 100 to determinewhether or not an occlusion (e.g., a blockage) has occurred within e.g.cannula assembly 114.

Referring also to FIGS. 18-19, occlusion detection process 238 maydetermine 1900 a rate-of-change force reading (e.g., FR01) thatcorresponds to the delivery of first dose 240 (FIG. 2) of infusiblefluid 200.

When determining 1900 the rate-of-change force reading (e.g., FR01),occlusion detection process 238 may determine 1902 an initial forcereading prior to dispensing first dose 240 of infusible fluid 200. Asdiscussed above, infusion pump assembly 100 may regularly dispenseindividual doses of infusible fluid 200 based upon one or more infusionschedules. For example and as discussed above, infusion pump assembly100 may be configured to dispense 0.10 mL of infusible fluid 200 to user202 every three minutes.

When determining 1902 the initial force reading prior to dispensingfirst dose 240 of infusible fluid 200, occlusion detection process 238may obtain the initial force reading from force sensor 216. Providedthat there is not an occlusion within e.g. cannula assembly 114, theinitial force reading obtained by occlusion detection process 238 priorto infusion pump assembly 100 dispensing first dose 240 of infusiblefluid 200 should be zero pounds. Once occlusion detection process 238determines 1902 the initial force reading, infusion pump assembly 100may dispense 1904 first dose 240 of infusible fluid 200 to user 202 viacannula assembly 114. While the system may be described above and/orbelow as having a force reading of zero pounds prior to and/orsubsequent to dispensing infusible fluid 200, this is for illustrativepurposes only, as frictional forces and/or backpressure may result inforce readings that are slightly higher than zero pounds.

Once infusion pump assembly 100 dispenses 1904 first dose 240 ofinfusible fluid 200 to user 202, occlusion detection process 238 maydetermine 1906 a final force reading subsequent to dispensing 1904 firstdose 240 of infusible fluid 200. For example, once infusion pumpassembly 100 has completely dispensed 1904 first dose 240 of infusiblefluid 200 to user 202, occlusion detection process 238 may obtain thefinal force reading from force sensor 216 in a process similar to thatused to obtain the initial force reading from force sensor 216.

Occlusion detection process 238 may determine 1900 the rate-of-changeforce reading (e.g., FRO1) based, at least in part, upon the initialforce reading and the final force reading. For example, occlusiondetection process 238 may subtract the initial force reading from thefinal force reading to determine the net force change that occurredwhile dispensing (in this particular example) 0.10 mL of infusible fluid200. As discussed above, provided that there are no occlusions withine.g. cannula assembly 114, the initial force reading (obtained fromforce sensor 216) should be zero and the final force reading (alsoobtained from force sensor 216) should also be zero. Accordingly, therate-of-change force reading (e.g., FRO1) determined 1900 by occlusiondetection process 238 should also be zero.

While the system is described above as determining 1906 a final forcereading subsequent to dispensing 1904 first dose 240 of infusible fluid200, this final force reading may actually be based upon the initialforce reading that is taken for the next dose of infusible fluid 200.Accordingly, by allowing the initial force reading of the second dose ofinfusible fluid 200 to provide the data for the final force reading ofthe first dose of infusible fluid 200, the total number of forcereadings made may be reduced by 50%.

Once the rate-of-change force reading (e.g., FRO1) is determined,occlusion detection process 238 may store the rate-of-change forcereading (e.g., FRO1) within e.g., storage cell 1800 of storage array1802. Storage array 1802 may be configured as a FIFO (first in, firstout) buffer. Storage array 1802 may be configured to allow occlusiondetection process 238 to maintain a plurality of historical values forthe rate-of-change force readings (e.g., FRO1) discussed above. Atypical embodiment of storage array 1802 may include twenty or fortyindividual storage cells. While storage array 1802 is illustrated inFIG. 18 as being a multi-column storage array, this is for illustrativepurposes only and is not intended to be a limitation of this disclosure.For example, storage array 1802 may be a single column storage array inwhich only the rate-of-change force readings are stored.

Occlusion detection process 238 may process the historical values of therate-of-change force readings to determine an average rate-of-changeforce reading over a desired infusible fluid volume/number of infusioncycles. For example, occlusion detection process 238 may determine anaverage rate-of-change force reading over each forty infusion cycles.Accordingly, occlusion detection process 238 may determine 1908additional rate-of-change force readings, each of which corresponds tothe delivery of additional doses of infusible fluid 200. For example andfor illustrative purposes only, occlusion detection process 238 maydetermine 1908 thirty-nine additional rate-of-change force readings forthe next thirty-nine infusion cycles. Each of these thirty-ninerate-of-change force readings may be stored in a unique storage cell ofstorage array 1802. Once storage array 1802 is completely full (i.e.contains forty rate-of-change force readings), occlusion detectionprocess 238 may determine an average rate-of-change force reading forthe set of forty rate-of-change force readings. Once this averagerate-of-change force reading is determined, storage array 1802 may becleared and the process of gathering additional rate-of-change forcereadings may be repeated.

When determining additional rate-of-change force readings, occlusiondetection process 238 may determine 1910 an initial force reading priorto dispensing the additional dose (e.g., dose 242) of infusible fluid200. Dose 242 of infusible fluid may then be dispensed 1912 by infusionpump assembly 100. Occlusion detection process 238 may determine 1914 afinal force reading subsequent to dispensing dose 242 of infusible fluid200.

Occlusion detection process 238 may determine 1908 the additionalrate-of-change force readings (e.g., FR2) based, at least in part, uponthe initial force reading and the final force reading for eachadditional dose of infusible fluid 200. As discussed above, providedthat there are no occlusions within e.g. cannula assembly 114, theinitial force reading (obtained from force sensor 216) should be zeroand the final force reading (also obtained from force sensor 216) shouldalso be zero. Accordingly, the rate-of-change force reading (e.g., FR2)determined 1908 by occlusion detection process 238 should also be zero.As discussed above, once the additional rate-of-change force readings(e.g., FR2) are determined, occlusion detection process 238 may storethe rate-of-change force reading (e.g., FR2) within e.g., storage cell1804 of storage array 1802.

Assume for illustrative purposes that occlusion detection process 238continues to calculate the rate-of-change force readings in the mannerdescribed above and continues to store these calculated rate-of-changeforce readings within storage array 1802. Further, assume forillustrative purposes that infusion pump assembly 100 continues tooperate properly (i.e. without any occlusions) for the firstthirty-three infusion cycles. Accordingly, the first thirty-threerate-of-change force readings (FR01-FR33) are all zero, as theirrespective initial force reading and final force reading were all zero.However, assume for illustrative purposes that an occlusion (e.g.occlusion 244) occurs within cannula assembly 114 prior to calculatingthe thirty-fourth, rate-of-change force reading (e.g., FR34), which isstored within storage cell 1806. Assume for illustrative purposes thatwhen determining the thirty-fourth rate-of-change force reading (e.g.,FR34), occlusion detection process 238 determines 1910 an initial forcereading of 0.00 pounds. When infusion pump assembly 100 begins todispense 1912 the thirty-fourth dose of infusible fluid 200, asocclusion 244 is present within cannula assembly 114, the fluiddisplaced from reservoir assembly 200 by plunger assembly 224 will notbe able to pass through cannula assembly 114. Accordingly, the pressurewithin reservoir assembly 200 will begin to build. Therefore, assume forillustrative purposes that occlusion detection process 238 determines1914 a final force reading of 0.50 pounds. Accordingly, occlusiondetection process 238 may determine 1908 the rate-of-change forcereading (e.g., FR34) to be 0.50 pounds minus 0.00 pounds, for arate-of-change of 0.50 pounds.

Due to the presence of occlusion 244 within cannula assembly 114, whenmotor assembly 214 attempts to dispense the next dose of infusible fluid200, 0.50 pounds of pressure sensed by force sensor 216 will still bepresent within fluid reservoir 200. Accordingly, when determining thethirty-fifth rate-of-change force reading (e.g., FR35), the initialforce reading determined 1910 by occlusion detection process 238 may bethe same as the final force reading determined by occlusion detectionprocess 238 when determining the thirty-fourth rate-of-change forcereading (e.g., FR34)

Occlusion detection process 238 may determine 1916 an averagerate-of-change force reading (e.g., AFR) based, at least in part, uponall or a portion of the rate-of-change force readings included withinstorage array 1802. Assume for illustrative purposes that occlusiondetection process 238 is configured to consider all rate-of-change forcereadings (e.g., FR01-FR40) included within storage array 1802.Accordingly, occlusion detection process 238 may calculate themathematical average of all rate-of-change force readings (e.g.,FR01-FR40) included within storage array 1802. In this particularexample, average rate-of-change force reading (e.g., AFR) has amathematical value of 0.105 pounds. While the system is described aboveas being capable of considering all rate-of-change force readings (e.g.,FR01-FR40) included within storage array 1802, this is for illustrativepurposes only and is not intended to be a limitation of this disclosure,as other configurations are possible. For example, occlusion detectionprocess 238 may be configured to determine 1916 an averagerate-of-change force reading (e.g., AFR) once storage array 1802 ispopulated with e.g., the first five rate-of-change force readings. Ifdetermining 1916 an average rate-of-change force reading (e.g., AFR)prior to storage array 1802 being completely populated, any unpopulatedrows within storage array 1802 may be populated with zeros.

Occlusion detection process 238 may compare 1918 the averagerate-of-change force reading (e.g., AFR) to a threshold rate-of-changeforce reading to determine if the average rate-of-change force reading(e.g., AFR) exceeds the threshold rate-of-change force reading. If theaverage rate-of-change force reading does not exceed the thresholdrate-of-change force reading, infusion pump assembly 100 may continue1920 to operate normally. However, if the average rate-of-change forcereading exceeds the threshold rate-of-change force reading, an alarmsequence may be initiated 1922 on infusion pump assembly 100. Forexample, assuming for illustrative purposes that occlusion detectionprocess 238 is configured to have a threshold rate-of-change forcereading of 0.90 pounds, only after the average rate-of-change forcereading (e.g., AFR) exceeds 0.90 pounds will the alarm sequence beinitiated 1920. Thus, in these embodiments, measuring the rate-of-changemay ensure alarm sequences are triggered more reliably when actualocclusions have occurred. As described below, user 202, in someembodiments, defines the sensitivity of the system.

The sensitivity of occlusion detection process 238 may be based upon auser-defined sensitivity setting selected 1924 by e.g., user 202. Forexample, assume that occlusion detection process 238 has two sensitivitysettings, namely a high sensitivity setting and a low sensitivitysetting. Further, assume that each of the sensitivity settings isassociated with a unique manner of determining the rate-of-change forcereadings included within storage array 1802. As discussed above,occlusion detection process 238 is described above as determining 1900 arate-of-change force reading (e.g., FRO1) that corresponds to thedelivery of first dose 240 of infusible fluid 200. Assume that whenconfigured in the high sensitivity setting, occlusion detection process238 may determine 1900 a rate-of-change force reading that correspondsto the delivery of a comparatively smaller quantity of infusible fluid200. Further, assume that when configured in the low sensitivitysetting, occlusion detection process 238 may determine 1900 arate-of-change force reading that corresponds to the delivery of acomparatively larger quantity of infusible fluid 200. For example,assume that when in the high sensitivity setting, occlusion detectionprocess 238 determines 1900 a rate-of-change force reading thatcorresponds to the delivery of 0.10 mL of infusible fluid 200. Further,assume that when in the low sensitivity setting, occlusion detectionprocess 238 determines 1900 a rate-of-change force reading thatcorresponds to the delivery of a 0.20 mL dose 240 of infusible fluid200. Accordingly, when placed in the high sensitivity setting,additional measurements are taken and occlusion detection process 238 ismore responsive. However, false alarms may occur more frequently.Conversely, when placed in the low sensitivity setting, fewermeasurements are taken and occlusion detection process 238 is lessresponsive. However, false alarms may occur less frequently due to the“averaging” effect of taking fewer measurements. Accordingly, in orderto avoid nuisance alarms (or to reduce the number of alarms), the user(e.g. user 202) may select 1924 the low sensitivity setting.

The alarm sequence initiated 1922 may include any combination ofvisual-based (via display system 104), audible-based (via a audio system212), and vibration-based alarms (via vibration system 210). User 202may be able to select between the high-sensitivity setting and thelow-sensitivity setting via one or more of input system 208 and displaysystem 104.

While infusion pump assembly 100 is described above as delivering aplurality of identically-sized doses of infusible fluid 200 andcalculating a rate-of-change force reading (e.g., FR01) for each dose ofinfusible fluid 200, this is for illustrative purposes only and is notintended to be a limitation of this disclosure. Specifically, infusionpump assembly 100 may be configured to provide non-identical doses ofinfusible fluid 200. Further and as discussed above, infusion pumpassembly 100 may be configured to allow user 202 to manually administera “bolus” dose of infusible fluid 200 in a size determined by user 202.Accordingly, occlusion detection process 238 may be configured tomonitor the volume of infusible fluid 200 dispensed in each dose and maybe configured to populate storage array 1802 so that each rate-of-changeforce reading (e.g., FR01) included within storage array 1802 isindicative of the rate-of-change force sensed by occlusion detectionprocess 238 when dispensing an equivalent quantity of infusible fluid200. Accordingly, occlusion detection process 238 may be configured to“normalize” the rate-of-change force readings determined based upon thequantity of infusible fluid delivered.

For example, assume that occlusion detection process 238 is configuredso that a storage cell included within storage array 1802 is populatedeach time 0.10 mL of infusible fluid 200 is dispensed. Assume forillustrative purposes only that user 202 decides to dispense a 0.25 mLdose of infusible fluid 200. As the 0.25 mL dose of infusible fluid 200is greater than the 0.10 mL increments at which occlusion detectionprocess 238 is configured to populate storage array 1802, occlusiondetection process 238 may record multiple entries (and, therefore,populate multiple storage cells) within storage array 1802 for thesingle 0.25 mL dose of infusible fluid 200.

Specifically, assume that the initial force reading determined 1910prior to delivering the 0.25 mL dose of infusible fluid 200 is 0.00pounds and the final force reading determined 1914 after dispensing 1912the 0.25 mL dose of infusible fluid 200 is 1.00 pounds. As the 0.25 mLdose of infusible fluid 200 is two-and-a-half times the 0.10 mLincrements in which occlusion detection process 238 is configured topopulate storage array 52, occlusion detection process 238 may“normalize” this rate-of-change force reading. Specifically, occlusiondetection process 238 may divide 1.00 pounds by 0.25 mL to determinethat the force changed 0.40 pounds per 0.10 mL. Accordingly, occlusiondetection process 238 may calculate a rate-of-change force reading of0.40 pounds for the first 0.10 mL dose of infusible fluid 200, 0.40pounds for the second 0.10 mL dose of infusible fluid 200, and 0.20pounds for the last 0.05 mL dose of infusible fluid 200.

Accordingly, occlusion detection process 238 may populate storage array1802 so that a first storage cell (associated with the first 0.10 mLdose of infusible fluid 200) defines an initial force reading of 0.00pounds, a final force reading of 0.40 pounds and a rate-of-change forcereading of 0.40 pounds. Further, occlusion detection process 238 maypopulate storage array 1802 so that a second storage cell (associatedwith the second 0.10 mL dose of infusible fluid 200) defines anadditional force reading of 0.40 pounds, a final force reading of 0.80pounds and a rate-of-change force reading of 0.40 pounds.

Concerning the remaining 0.05 mL of the 0.25 mL dose of infusible fluid200, as this is less than the 0.10 mL increment at which occlusiondetection process 238 is configured to populate storage array 52, thenext cell within storage array 1802 will not be populated until anadditional 0.05 mL dose of infusible fluid 200 is dispensed.

Continuing with the above-stated example, assume for illustrativepurposes that infusion pump assembly 100 administers a 0.15 mL dose ofinfusible fluid 200. Occlusion detection process 238 may combine thefirst 0.05 mL of the 0.15 mL dose of infusible fluid 200 with theremaining 0.05 mL of the 0.25 mL dose of infusible fluid 200 to form acomplete 0.10 mL increment for recording within storage array 1802.

Again, occlusion detection process 238 may “normalize” the 0.15 mL doseof infusible fluid 200. Assume for illustrative purposes that whendispensing the 0.15 mL of infusible fluid 200, occlusion detectionprocess 238 determines an initial force reading of 1.00 pounds and afinal force reading of 1.60 pounds. In the manner described above,occlusion detection process 238 may divide 0.60 pounds (i.e., 1.60pounds minus 1.00 pounds) by 0.15 mL to determine that the force changed0.40 pounds per 0.10 mL. Accordingly, occlusion detection process 238may calculate a rate-of-change force reading of 0.20 pounds for thefirst 0.05 mL of the 0.15 mL dose of infusible fluid 200, and 0.40pounds for the remaining 0.10 mL of the 0.15 mL dose of infusible fluid200.

Accordingly, occlusion detection process 238 may populate storage array1802 so that a third storage cell (associated with the combination ofthe first 0.05 mL of the 0.15 mL dose of infusible fluid 200 with theremaining 0.05 mL of the 0.25 mL dose of infusible fluid 200) defines aninitial force reading of 0.80 pounds (i.e., which is the final forcereading after the second 0.10 mL of the 0.25 mL dose of infusible fluid200), a final force reading of 1.20 pounds (i.e., the sum of the initialforce reading of 1.00 pounds plus the 0.20 pound offset for the first0.05 mL of the 0.15 mL dose of infusible fluid 200) and a rate-of-changeforce reading of 0.40 pounds. Further, occlusion detection process 238may populate storage array 1802 so that a fourth storage cell(associated with the last 0.10 mL of the 0.15 mL dose of infusible fluid200) defines an initial force reading of 1.20 pounds, a final forcereading of 1.60 pounds and a rate-of-change force reading of 0.40pounds.

In addition to comparing 1918 the average rate-of-change force reading(e.g., AFR) to a threshold rate-of-change force reading to determine ifthe average rate-of-change force reading (e.g., AFR) exceeds thethreshold rate-of-change force reading, occlusion detection process 238may compare 1926 one or more of the initial force reading and the finalforce reading to a threshold force reading to determine if either theinitial force reading or the final force reading exceeds the thresholdforce reading. If either of the initial force reading or the final forcereading exceeds the threshold force reading, an alarm sequence maybeinitiated 1928 on infusion pump assembly 100.

For example, occlusion detection process 238 may define a thresholdforce reading, which if exceeded by either the initial force reading(which is determined prior to dispensing a dose of infusible fluid 200)or the final force reading (which is determined after dispensing a doseof infusible fluid 200), an occlusion is deemed to be occurring.Examples of such a threshold force reading is 4.00 pounds. Therefore, ifafter dispensing a dose of infusible fluid 200, occlusion detectionprocess 238 determines a final force reading of 5.20 pounds, occlusiondetection process 238 may initiate 1928 an alarm sequence, as 5.20pounds exceeds the 4.00 threshold force reading. The alarm sequenceinitiated 1928 may include any combination of visual-based (via displaysystem 104), audible-based (via audio system 212), and vibration-basedalarms (via vibration system 210).

As discussed above, infusion pump assembly 100 may include primary powersupply 220 configured to power infusion pump assembly 100. Before and/orafter dispensing a dose of infusible fluid 200, occlusion detectionprocess 238 may compare 1930 the actual voltage level of primary powersupply 220 to a minimum voltage requirement to determine if the actualvoltage level of primary power supply 220 meets the minimum voltagerequirement. If the actual voltage level does not meet the minimumvoltage requirement, occlusion detection process 238 may initiate 1932an alarm sequence on infusion pump assembly 100. The alarm sequenceinitiated 1932 may include any combination of visual-based (via displaysystem 104), audible-based (via audio system 212), and vibration-basedalarms (via vibration system 210). For example, assume for illustrativepurposes that primary power supply 220 is a 5.00 VDC battery. Further,assume that the minimum voltage requirement is 3.75 VDC (i.e., 75% ofnormal voltage). Accordingly, if occlusion detection process 238determines 1930 that the actual voltage level of primary power supply220 is 3.60 VDC, occlusion detection process 238 may initiate 1932 analarm sequence on infusion pump assembly 100.

Additionally, occlusion detection process 238 may monitor one or more ofthe displaceable mechanical components included within infusion pumpassembly 100 to determine 1934 if one or more displaceable mechanicalcomponents included within infusion pump assembly 100 were displaced anexpected displacement in response to delivering a dose of infusiblefluid 200. If the displaceable mechanical components monitored were notdisplaced the expected displacement in response to delivering a dose ofinfusible fluid 200, occlusion detection process 238 may initiate 1936an alarm sequence on infusion pump assembly 100. The alarm sequenceinitiated 1936 may include any combination of visual-based (via displaysystem 104), audible-based (via audio system 212), and vibration-basedalarms (via vibration system 210).

For example, upon processing logic 204 energizing motor assembly 214 todispense 0.10 mL of infusible fluid 200, occlusion detection process 238may (via displacement detection device 218) confirm that partial nutassembly 226 did indeed move the expected displacement. Accordingly, inthe event that partial nut assembly 226 does not move the expecteddisplacement, a mechanical failure (e.g. the failure of partial nutassembly 226, the failure of lead screw assembly 228, the failure ofmotor assembly 214) may have occurred. In the event that the expecteddisplacement of partial nut assembly 226 cannot be confirmed, occlusiondetection process 238 may initiate 1936 the alarm sequence on infusionpump assembly 100.

When determining whether partial nut assembly 226 was displaced theexpected amount, tolerances may be utilized. For example, assume that todeliver a 0.10 mL dose of infusible fluid 200, occlusion detectionprocess 238 may expect to see partial nut assembly 226 displaced 0.050inches. Accordingly, occlusion detection process 238 may utilize a 10%error window in which movement of partial nut assembly 226 of less than0.045 inches (i.e., 10% less than expected) would result in occlusiondetection process 238 initiating 1936 the alarm sequence on infusionpump assembly 100.

In one embodiment of displacement detection device 218, displacementdetection device 218 includes one or more light sources (not shown)positioned on one side of partial nut assembly 226 and one or more lightdetectors (not shown) positioned on the other side of partial nutassembly 226. Partial nut assembly 226 may include one or more passages(not shown) through which the light from the one or more light sources(not shown) included within displacement detection device 218 may shineand may be detected by the one or more light detectors (not shown)included within displacement detection device 218.

Referring now to FIG. 20, in some embodiments of the infusion pumpsystem, the infusion pump may be remotely controlled using remotecontrol assembly 2000. Remote control assembly 2000 may include all, ora portion of, the functionality of the pump assembly itself. Thus, insome exemplary embodiments of the above-described infusion pumpassembly, the infusion pump assembly (not shown, see FIGS. 1A-1F,amongst other FIGS.) may be configured via remote control assembly 2000.In these particular embodiments, the infusion pump assembly may includetelemetry circuitry (not shown) that allows for communication (e.g.,wired or wireless) between the infusion pump assembly and e.g., remotecontrol assembly 2000, thus allowing remote control assembly 2000 toremotely control infusion pump assembly 100′. Remote control assembly2000 (which may also include telemetry circuitry (not shown) and may becapable of communicating with infusion pump assembly) may includedisplay assembly 2002 and an input assembly, which may include one ormore of the following: an input control device (such as jog wheel 2006,slider assembly 2012, or another conventional mode for input into adevice), and switch assemblies 2008, 2010. Thus, although remote controlassembly 2000 as shown in FIG. 20 includes jog wheel 2006 and sliderassembly 2012, some embodiments may include only one of either jog wheel2006 or slider assembly 2012, or another conventional mode for inputinto a device. In embodiments having jog wheel 2006, jog wheel 2006 mayinclude a wheel, ring, knob, or the like, that may be coupled to arotary encoder, or other rotary transducer, for providing a controlsignal based upon, at least in part, movement of the wheel, ring, knob,or the like.

Remote control assembly 2000 may include the ability to pre-programbasal rates, bolus alarms, delivery limitations, and allow the user toview history and to establish user preferences. Remote control assembly2000 may also include glucose strip reader 2014.

During use, remote control assembly 2000 may provide instructions to theinfusion pump assembly via a wireless communication channel establishedbetween remote control assembly 2000 and the infusion pump assembly.Accordingly, the user may use remote control assembly 2000 toprogram/configure the infusion pump assembly. Some or all of thecommunication between remote control assembly 2000 and the infusion pumpassembly may be encrypted to provide an enhanced level of security.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made. Accordingly, otherimplementations are within the scope of the following claims.

What is claimed is:
 1. A delivery device for delivering an infusionmedium to a user, the device comprising: first and second housingportions configured to be selectively engaged together for operation andselectively separated from each other; a reservoir supported by thefirst housing portion, the reservoir including a reservoir housinghaving an interior volume; a plunger head moveable to selectively changethe volume of the reservoir interior; a rod extending from the plungerhead to a position outside of the reservoir housing, wherein the plungerrod comprises a detectable feature; and a sensor arranged to detect thedetectable feature to provide a signal corresponding to the position ofthe detectable feature.
 2. The device of claim 1, further comprising anut member being supported in fixed relation with the plunger rod, thenut member having a structure for engaging the plunger rod in any one ofa plurality of positions in a first dimension relative to the nutmember.
 3. The device of claim 2, wherein the nut member includes adetectable feature.
 4. The device of claim 1, further comprising alocking tab.
 5. The device of claim 4, further comprising a pump barrelinside a pump barrel housing, the pump barrel accommodates thereservoir.
 6. The device of claim 5, further comprising a locking discat a terminus of the pump barrel, the locking disc having a clearancehole for the plunger rod and at least one locking tab notch, the lockingdisc being in close proximity with the locking tab.
 7. The device ofclaim 6, wherein the locking disc rotates upon torque being applied tothe reservoir, the locking disc rotating from a-non-loaded position to aloaded position with respect to said plunger rod and a drive screw.
 8. Adelivery device for delivering an infusion medium to a user, the devicecomprising: first and second housing portions configured to beselectively engaged together for operation and selectively separatedfrom each other; a reservoir supported by the first housing portion, thereservoir including a reservoir housing having an interior volume; aplunger moveable to selectively change the volume of the reservoirinterior; and a plunger rod extending from the plunger, the plunger rodincluding a threaded portion having an open side, wherein the plungerrod includes a detectable feature; and a sensor arranged to detect thedetectable feature to provide a signal corresponding to the position ofthe detectable feature, wherein the position of the detectable featurecorresponds to a fill state of the reservoir.
 9. The device of claim 8,further comprising a drive screw supported by the second housing portionfor rotation about a rotary axis, the drive screw being engageable withthe threaded portion of the plunger rod as the first and second housingportions are brought together for operative engagement.
 10. The deviceof claim 8, wherein the nut member includes a detectable feature. 11.The device of claim 8, further comprising a locking tab.
 12. The deviceof claim 11, further comprising a pump barrel inside a pump barrelhousing, the pump barrel accommodates the reservoir.
 13. The device ofclaim 12, further comprising a locking disc at a terminus of the pumpbarrel, the locking disc having a clearance hole for the plunger rod andat least one locking tab notch, the locking disc being in closeproximity with the locking tab.
 14. The device of claim 13, wherein thelocking disc rotates upon torque being applied to the reservoir, thelocking disc rotating from a-non-loaded position to a loaded positionwith respect to said plunger rod and a drive screw.